diff --git a/doc/sphinx/Pacemaker_Explained/acls.rst b/doc/sphinx/Pacemaker_Explained/acls.rst index 878f8f64b3..f1f052505a 100644 --- a/doc/sphinx/Pacemaker_Explained/acls.rst +++ b/doc/sphinx/Pacemaker_Explained/acls.rst @@ -1,476 +1,476 @@ .. index:: single: Access Control List (ACL) .. _acl: Access Control Lists (ACLs) --------------------------- By default, the ``root`` user or any user in the |CRM_DAEMON_GROUP| group can modify Pacemaker's CIB without restriction. Pacemaker offers *access control lists (ACLs)* to provide more fine-grained authorization. .. important:: Being able to modify the CIB's resource section allows a user to run any executable file as root, by configuring it as an LSB resource with a full path. ACL Prerequisites ################# In order to use ACLs: * The ``enable-acl`` :ref:`cluster option ` must be set to true. * Desired users must have user accounts in the |CRM_DAEMON_GROUP| group on all cluster nodes in the cluster. * If your CIB was created before Pacemaker 1.1.12, it might need to be updated to the current schema (using ``cibadmin --upgrade`` or a higher-level tool equivalent) in order to use the syntax documented here. * Prior to the 2.1.0 release, the Pacemaker software had to have been built with ACL support. If you are using an older release, your installation supports ACLs only if the output of the command ``pacemakerd --features`` contains ``acls``. In newer versions, ACLs are always enabled. .. important:: ``enable-acl`` should be set either by the root user, or as part of a batch of CIB changes including roles and users. Otherwise, the user setting it might lock themselves out from making any further changes. .. index:: single: Access Control List (ACL); acls pair: acls; XML element ACL Configuration ################# ACLs are specified within an ``acls`` element of the CIB. The ``acls`` element may contain any number of ``acl_role``, ``acl_target``, and ``acl_group`` elements. .. index:: single: Access Control List (ACL); acl_role pair: acl_role; XML element ACL Roles ######### An ACL *role* is a collection of permissions allowing or denying access to particular portions of the CIB. A role is configured with an ``acl_role`` element in the CIB ``acls`` section. .. table:: **Properties of an acl_role element** - :widths: 1 3 + :widths: 25 75 +------------------+-----------------------------------------------------------+ | Attribute | Description | +==================+===========================================================+ | id | .. index:: | | | single: acl_role; id (attribute) | | | single: id; acl_role attribute | | | single: attribute; id (acl_role) | | | | | | A unique name for the role *(required)* | +------------------+-----------------------------------------------------------+ | description | .. index:: | | | single: acl_role; description (attribute) | | | single: description; acl_role attribute | | | single: attribute; description (acl_role) | | | | | | Arbitrary text for user's use (ignored by Pacemaker) | +------------------+-----------------------------------------------------------+ An ``acl_role`` element may contain any number of ``acl_permission`` elements. .. index:: single: Access Control List (ACL); acl_permission pair: acl_permission; XML element .. table:: **Properties of an acl_permission element** - :widths: 1 3 + :widths: 25 75 +------------------+-----------------------------------------------------------+ | Attribute | Description | +==================+===========================================================+ | id | .. index:: | | | single: acl_permission; id (attribute) | | | single: id; acl_permission attribute | | | single: attribute; id (acl_permission) | | | | | | A unique name for the permission *(required)* | +------------------+-----------------------------------------------------------+ | description | .. index:: | | | single: acl_permission; description (attribute) | | | single: description; acl_permission attribute | | | single: attribute; description (acl_permission) | | | | | | Arbitrary text for user's use (ignored by Pacemaker) | +------------------+-----------------------------------------------------------+ | kind | .. index:: | | | single: acl_permission; kind (attribute) | | | single: kind; acl_permission attribute | | | single: attribute; kind (acl_permission) | | | | | | The access being granted. Allowed values are ``read``, | | | ``write``, and ``deny``. A value of ``write`` grants both | | | read and write access. | +------------------+-----------------------------------------------------------+ | object-type | .. index:: | | | single: acl_permission; object-type (attribute) | | | single: object-type; acl_permission attribute | | | single: attribute; object-type (acl_permission) | | | | | | The name of an XML element in the CIB to which the | | | permission applies. (Exactly one of ``object-type``, | | | ``xpath``, and ``reference`` must be specified for a | | | permission.) | +------------------+-----------------------------------------------------------+ | attribute | .. index:: | | | single: acl_permission; attribute (attribute) | | | single: attribute; acl_permission attribute | | | single: attribute; attribute (acl_permission) | | | | | | If specified, the permission applies only to | | | ``object-type`` elements that have this attribute set (to | | | any value). If not specified, the permission applies to | | | all ``object-type`` elements. May only be used with | | | ``object-type``. | +------------------+-----------------------------------------------------------+ | reference | .. index:: | | | single: acl_permission; reference (attribute) | | | single: reference; acl_permission attribute | | | single: attribute; reference (acl_permission) | | | | | | The ID of an XML element in the CIB to which the | | | permission applies. (Exactly one of ``object-type``, | | | ``xpath``, and ``reference`` must be specified for a | | | permission.) | +------------------+-----------------------------------------------------------+ | xpath | .. index:: | | | single: acl_permission; xpath (attribute) | | | single: xpath; acl_permission attribute | | | single: attribute; xpath (acl_permission) | | | | | | An `XPath `_ | | | specification selecting an XML element in the CIB to | | | which the permission applies. Attributes may be specified | | | in the XPath to select particular elements, but the | | | permissions apply to the entire element. (Exactly one of | | | ``object-type``, ``xpath``, and ``reference`` must be | | | specified for a permission.) | +------------------+-----------------------------------------------------------+ .. important:: * Permissions are applied to the selected XML element's entire XML subtree (all elements enclosed within it). * Write permission grants the ability to create, modify, or remove the element and its subtree, and also the ability to create any "scaffolding" elements (enclosing elements that do not have attributes other than an ID). * Permissions for more specific matches (more deeply nested elements) take precedence over more general ones. * If multiple permissions are configured for the same match (for example, in different roles applied to the same user), any ``deny`` permission takes precedence, then ``write``, then lastly ``read``. ACL Targets and Groups ###################### ACL targets correspond to user accounts on the system. .. index:: single: Access Control List (ACL); acl_target pair: acl_target; XML element .. table:: **Properties of an acl_target element** - :widths: 1 3 + :widths: 25 75 +------------------+-----------------------------------------------------------+ | Attribute | Description | +==================+===========================================================+ | id | .. index:: | | | single: acl_target; id (attribute) | | | single: id; acl_target attribute | | | single: attribute; id (acl_target) | | | | | | A unique identifier for the target (if ``name`` is not | | | specified, this must be the name of the user account) | | | *(required)* | +------------------+-----------------------------------------------------------+ | name | .. index:: | | | single: acl_target; name (attribute) | | | single: name; acl_target attribute | | | single: attribute; name (acl_target) | | | | | | If specified, the user account name (this allows you to | | | specify a user name that is already used as the ``id`` | | | for some other configuration element) *(since 2.1.5)* | +------------------+-----------------------------------------------------------+ ACL groups correspond to groups on the system. Any role configured for these groups apply to all users in that group *(since 2.1.5)*. .. index:: single: Access Control List (ACL); acl_group pair: acl_group; XML element .. table:: **Properties of an acl_group element** - :widths: 1 3 + :widths: 25 75 +------------------+-----------------------------------------------------------+ | Attribute | Description | +==================+===========================================================+ | id | .. index:: | | | single: acl_group; id (attribute) | | | single: id; acl_group attribute | | | single: attribute; id (acl_group) | | | | | | A unique identifier for the group (if ``name`` is not | | | specified, this must be the group name) *(required)* | +------------------+-----------------------------------------------------------+ | name | .. index:: | | | single: acl_group; name (attribute) | | | single: name; acl_group attribute | | | single: attribute; name (acl_group) | | | | | | If specified, the group name (this allows you to specify | | | a group name that is already used as the ``id`` for some | | | other configuration element) | +------------------+-----------------------------------------------------------+ Each ``acl_target`` and ``acl_group`` element may contain any number of ``role`` elements. .. note:: If the system users and groups are defined by some network service (such as LDAP), the cluster itself will be unaffected by outages in the service, but affected users and groups will not be able to make changes to the CIB. .. index:: single: Access Control List (ACL); role pair: role; XML element .. table:: **Properties of a role element** - :widths: 1 3 + :widths: 25 75 +------------------+-----------------------------------------------------------+ | Attribute | Description | +==================+===========================================================+ | id | .. index:: | | | single: role; id (attribute) | | | single: id; role attribute | | | single: attribute; id (role) | | | | | | The ``id`` of an ``acl_role`` element that specifies | | | permissions granted to the enclosing target or group. | +------------------+-----------------------------------------------------------+ .. important:: The ``root`` and |CRM_DAEMON_USER| user accounts always have full access to the CIB, regardless of ACLs. For all other user accounts, when ``enable-acl`` is true, permission to all parts of the CIB is denied by default (permissions must be explicitly granted). ACLs and Pacemaker Remote Nodes ############################### ACLs apply differently on Pacemaker Remote nodes, which are assumed to be special-purpose hosts without typical user accounts. Instead, CIB modifications coming from a Pacemaker Remote node use the node's name as the ACL user name, and ``pacemaker-remote`` as the role. ACL Examples ############ .. code-block:: xml In the above example, the user ``alice`` has the minimal permissions necessary to run basic Pacemaker CLI tools, including using ``crm_mon`` to view the cluster status, without being able to modify anything. The user ``bob`` can view the entire configuration and status of the cluster, but not make any changes. The user ``carol`` can read everything, and change selected cluster properties as well as resource roles and location constraints. Finally, ``dave`` has full read and write access to the entire CIB. Looking at the ``minimal`` role in more depth, it is designed to allow read access to the ``cib`` tag itself, while denying access to particular portions of its subtree (which is the entire CIB). This is because the DC node is indicated in the ``cib`` tag, so ``crm_mon`` will not be able to report the DC otherwise. However, this does change the security model to allow by default, since any portions of the CIB not explicitly denied will be readable. The ``cib`` read access could be removed and replaced with read access to just the ``crm_config`` and ``status`` sections, for a safer approach at the cost of not seeing the DC in status output. For a simpler configuration, the ``minimal`` role allows read access to the entire ``crm_config`` section, which contains cluster properties. It would be possible to allow read access to specific properties instead (such as ``stonith-enabled``, ``dc-uuid``, ``have-quorum``, and ``cluster-name``) to restrict access further while still allowing status output, but cluster properties are unlikely to be considered sensitive. ACL Limitations ############### Actions performed via IPC rather than the CIB _____________________________________________ ACLs apply *only* to the CIB. That means ACLs apply to command-line tools that operate by reading or writing the CIB, such as ``crm_attribute`` when managing permanent node attributes, ``crm_mon``, and ``cibadmin``. However, command-line tools that communicate directly with Pacemaker daemons via IPC are not affected by ACLs. For example, users in the |CRM_DAEMON_GROUP| group may still do the following, regardless of ACLs: * Query transient node attribute values using ``crm_attribute`` and ``attrd_updater``. * Query basic node information using ``crm_node``. * Erase resource operation history using ``crm_resource``. * Query fencing configuration information, and execute fencing against nodes, using ``stonith_admin``. ACLs and Pacemaker Remote _________________________ ACLs apply to commands run on Pacemaker Remote nodes using the Pacemaker Remote node's name as the ACL user name. The idea is that Pacemaker Remote nodes (especially virtual machines and containers) are likely to be purpose-built and have different user accounts from full cluster nodes. diff --git a/doc/sphinx/Pacemaker_Explained/alerts.rst b/doc/sphinx/Pacemaker_Explained/alerts.rst index b573bcf2d4..fc5ca94eae 100644 --- a/doc/sphinx/Pacemaker_Explained/alerts.rst +++ b/doc/sphinx/Pacemaker_Explained/alerts.rst @@ -1,297 +1,297 @@ .. _alerts: .. index:: single: alert single: resource; alert single: node; alert single: fencing; alert pair: XML element; alert pair: XML element; alerts Alerts ------ *Alerts* may be configured to take some external action when a cluster event occurs (node failure, resource starting or stopping, etc.). .. index:: pair: alert; agent Alert Agents ############ As with resource agents, the cluster calls an external program (an *alert agent*) to handle alerts. The cluster passes information about the event to the agent via environment variables. Agents can do anything desired with this information (send an e-mail, log to a file, update a monitoring system, etc.). .. topic:: Simple alert configuration .. code-block:: xml In the example above, the cluster will call ``my-script.sh`` for each event. Multiple alert agents may be configured; the cluster will call all of them for each event. Alert agents will be called only on cluster nodes. They will be called for events involving Pacemaker Remote nodes, but they will never be called *on* those nodes. For more information about sample alert agents provided by Pacemaker and about developing custom alert agents, see the *Pacemaker Administration* document. .. index:: single: alert; recipient pair: XML element; recipient Alert Recipients ################ Usually, alerts are directed towards a recipient. Thus, each alert may be additionally configured with one or more recipients. The cluster will call the agent separately for each recipient. .. topic:: Alert configuration with recipient .. code-block:: xml In the above example, the cluster will call ``my-script.sh`` for each event, passing the recipient ``some-address`` as an environment variable. The recipient may be anything the alert agent can recognize -- an IP address, an e-mail address, a file name, whatever the particular agent supports. .. index:: single: alert; meta-attributes single: meta-attribute; alert meta-attributes Alert Meta-Attributes ##################### As with resources, meta-attributes can be configured for alerts to change whether and how Pacemaker calls them. .. table:: **Meta-Attributes of an Alert or Recipient** :class: longtable - :widths: 1 1 3 + :widths: 20 20 60 +------------------+---------------+-----------------------------------------------------+ | Meta-Attribute | Default | Description | +==================+===============+=====================================================+ | description | | .. index:: | | | | single: acl_permission; description (attribute) | | | | single: description; acl_permission attribute | | | | single: attribute; description (acl_permission) | | | | | | | | Arbitrary text for user's use (ignored by Pacemaker)| +------------------+---------------+-----------------------------------------------------+ | enabled | true | .. index:: | | | | single: alert; meta-attribute, enabled | | | | single: meta-attribute; enabled (alert) | | | | single: enabled; alert meta-attribute | | | | | | | | If false for an alert, the alert will not be used. | | | | If true for an alert and false for a particular | | | | recipient of that alert, that recipient will not be | | | | used. *(since 2.1.6)* | +------------------+---------------+-----------------------------------------------------+ | timestamp-format | %H:%M:%S.%6N | .. index:: | | | | single: alert; meta-attribute, timestamp-format | | | | single: meta-attribute; timestamp-format (alert) | | | | single: timestamp-format; alert meta-attribute | | | | | | | | Format the cluster will use when sending the | | | | event's timestamp to the agent. This is a string as | | | | used with the ``date(1)`` command, with the | | | | following extension. ``"%xN"``, where ``x`` is a | | | | number with ``1 <= x <= 6``, prints the fractional | | | | seconds component of the timestamp at ``10^(-x)`` | | | | resolution, without a decimal point (``'.'``). | | | | Values are truncated toward zero, not rounded. | | | | | | | | Note: This is implemented using ``strftime()`` with | | | | a 128-character buffer. If any format specifier's | | | | expansion requires more than 128 characters, or if | | | | any specifier expands to an empty string, then the | | | | timestamp is discarded. (Expanding to an empty | | | | string is not an error, but there is no way to | | | | distinguish this from a too-small buffer.) | +------------------+---------------+-----------------------------------------------------+ | timeout | 30s | .. index:: | | | | single: alert; meta-attribute, timeout | | | | single: meta-attribute; timeout (alert) | | | | single: timeout; alert meta-attribute | | | | | | | | If the alert agent does not complete within this | | | | amount of time, it will be terminated. | +------------------+---------------+-----------------------------------------------------+ Meta-attributes can be configured per alert and/or per recipient. .. topic:: Alert configuration with meta-attributes .. code-block:: xml In the above example, the ``my-script.sh`` will get called twice for each event, with each call using a 15-second timeout. One call will be passed the recipient ``someuser@example.com`` and a timestamp in the format ``%D %H:%M``, while the other call will be passed the recipient ``otheruser@example.com`` and a timestamp in the format ``%c``. .. index:: single: alert; instance attributes single: instance attribute; alert instance attributes Alert Instance Attributes ######################### As with resource agents, agent-specific configuration values may be configured as instance attributes. These will be passed to the agent as additional environment variables. The number, names and allowed values of these instance attributes are completely up to the particular agent. .. topic:: Alert configuration with instance attributes .. code-block:: xml .. index:: single: alert; filters pair: XML element; select pair: XML element; select_nodes pair: XML element; select_fencing pair: XML element; select_resources pair: XML element; select_attributes pair: XML element; attribute Alert Filters ############# By default, an alert agent will be called for node events, fencing events, and resource events. An agent may choose to ignore certain types of events, but there is still the overhead of calling it for those events. To eliminate that overhead, you may select which types of events the agent should receive. Alert filters are configured within a ``select`` element inside an ``alert`` element. .. list-table:: **Possible alert filters** :class: longtable - :widths: 1 3 + :widths: 25 75 :header-rows: 1 * - Name - Events alerted * - select_nodes - A node joins or leaves the cluster (whether at the cluster layer for cluster nodes, or via a remote connection for Pacemaker Remote nodes). * - select_fencing - Fencing or unfencing of a node completes (whether successfully or not). * - select_resources - A resource action other than meta-data completes (whether successfully or not). * - select_attributes - A transient attribute value update is sent to the CIB. .. topic:: Alert configuration to receive only node events and fencing events .. code-block:: xml With ```` (the only event type not enabled by default), the agent will receive alerts when a node attribute changes. If you wish the agent to be called only when certain attributes change, you can configure that as well. .. topic:: Alert configuration to be called when certain node attributes change .. code-block:: xml Node attribute alerts are currently considered experimental. Alerts may be limited to attributes set via ``attrd_updater``, and agents may be called multiple times with the same attribute value. diff --git a/doc/sphinx/Pacemaker_Explained/cluster-options.rst b/doc/sphinx/Pacemaker_Explained/cluster-options.rst index 6ebe5f38eb..896d2f2229 100644 --- a/doc/sphinx/Pacemaker_Explained/cluster-options.rst +++ b/doc/sphinx/Pacemaker_Explained/cluster-options.rst @@ -1,936 +1,936 @@ Cluster-Wide Configuration -------------------------- .. index:: pair: XML element; cib pair: XML element; configuration Configuration Layout #################### The cluster is defined by the Cluster Information Base (CIB), which uses XML notation. The simplest CIB, an empty one, looks like this: .. topic:: An empty configuration .. code-block:: xml The empty configuration above contains the major sections that make up a CIB: * ``cib``: The entire CIB is enclosed with a ``cib`` element. Certain fundamental settings are defined as attributes of this element. * ``configuration``: This section -- the primary focus of this document -- contains traditional configuration information such as what resources the cluster serves and the relationships among them. * ``crm_config``: cluster-wide configuration options * ``nodes``: the machines that host the cluster * ``resources``: the services run by the cluster * ``constraints``: indications of how resources should be placed * ``status``: This section contains the history of each resource on each node. Based on this data, the cluster can construct the complete current state of the cluster. The authoritative source for this section is the local executor (pacemaker-execd process) on each cluster node, and the cluster will occasionally repopulate the entire section. For this reason, it is never written to disk, and administrators are advised against modifying it in any way. In this document, configuration settings will be described as properties or options based on how they are defined in the CIB: * Properties are XML attributes of an XML element. * Options are name-value pairs expressed as ``nvpair`` child elements of an XML element. Normally, you will use command-line tools that abstract the XML, so the distinction will be unimportant; both properties and options are cluster settings you can tweak. Options can appear within four types of enclosing elements: * ``cluster_property_set`` * ``instance_attributes`` * ``meta_attributes`` * ``utilization`` We will refer to a set of options and its enclosing element as a *block*. .. list-table:: **Properties of an Option Block's Enclosing Element** :class: longtable - :widths: 2 2 3 5 + :widths: 15 15 15 55 :header-rows: 1 * - Name - Type - Default - Description * - .. _option_block_id: .. index:: pair: id; cluster_property_set pair: id; instance_attributes pair: id; meta_attributes pair: id; utilization single: attribute; id (cluster_property_set) single: attribute; id (instance_attributes) single: attribute; id (meta_attributes) single: attribute; id (utilization) id - :ref:`id ` - - A unique name for the block (required) * - .. _option_block_score: .. index:: pair: score; cluster_property_set pair: score; instance_attributes pair: score; meta_attributes pair: score; utilization single: attribute; score (cluster_property_set) single: attribute; score (instance_attributes) single: attribute; score (meta_attributes) single: attribute; score (utilization) score - :ref:`score ` - 0 - Priority with which to process the block Each block may optionally contain a :ref:`rule `. .. _option_precedence: Option Precedence ################# This subsection describes the precedence of options within a set of blocks and within a single block. Options are processed as follows: * All option blocks of a given type are processed in order of their ``score`` attribute, from highest to lowest. For ``cluster_property_set``, if there is a block whose enclosing element has ``id="cib-bootstrap-options"``, then that block is always processed first regardless of score. * If a block contains a rule that evaluates to false, that block is skipped. * Within a block, options are processed in order from first to last. * The first value found for a given option is applied, and the rest are ignored. Note that this means it is pointless to configure the same option twice in a single block, because occurrences after the first one would be ignored. For example, in the following configuration snippet, the ``no-quorum-policy`` value ``demote`` is applied. ``property-set2`` has a higher score than ``property-set1``, so it's processed first. There are no rules in this snippet, so both sets are processed. Within ``property-set2``, the value ``demote`` appears first, so the later value ``freeze`` is ignored. We've already found a value for ``no-quorum-policy`` before we begin processing ``property-set1``, so its value ``stop`` is ignored. .. code-block:: xml CIB Properties ############## Certain settings are defined by CIB properties (that is, attributes of the ``cib`` tag) rather than with the rest of the cluster configuration in the ``configuration`` section. The reason is simply a matter of parsing. These options are used by the configuration database which is, by design, mostly ignorant of the content it holds. So the decision was made to place them in an easy-to-find location. .. list-table:: **CIB Properties** :class: longtable - :widths: 2 2 2 5 + :widths: 20 15 10 55 :header-rows: 1 * - Name - Type - Default - Description * - .. _admin_epoch: .. index:: pair: admin_epoch; cib admin_epoch - :ref:`nonnegative integer ` - 0 - When a node joins the cluster, the cluster asks the node with the highest (``admin_epoch``, ``epoch``, ``num_updates``) tuple to replace the configuration on all the nodes -- which makes setting them correctly very important. ``admin_epoch`` is never modified by the cluster; you can use this to make the configurations on any inactive nodes obsolete. * - .. _epoch: .. index:: pair: epoch; cib epoch - :ref:`nonnegative integer ` - 0 - The cluster increments this every time the CIB's configuration section is updated. * - .. _num_updates: .. index:: pair: num_updates; cib num_updates - :ref:`nonnegative integer ` - 0 - The cluster increments this every time the CIB's configuration or status sections are updated, and resets it to 0 when epoch changes. * - .. _validate_with: .. index:: pair: validate-with; cib validate-with - :ref:`enumeration ` - - Determines the type of XML validation that will be done on the configuration. Allowed values are ``none`` (in which case the cluster will not require that updates conform to expected syntax) and the base names of schema files installed on the local machine (for example, "pacemaker-3.9") * - .. _remote_tls_port: .. index:: pair: remote-tls-port; cib remote-tls-port - :ref:`port ` - - If set, the CIB manager will listen for anonymously encrypted remote connections on this port, to allow CIB administration from hosts not in the cluster. No key is used, so this should be used only on a protected network where man-in-the-middle attacks can be avoided. * - .. _remote_clear_port: .. index:: pair: remote-clear-port; cib remote-clear-port - :ref:`port ` - - If set to a TCP port number, the CIB manager will listen for remote connections on this port, to allow for CIB administration from hosts not in the cluster. No encryption is used, so this should be used only on a protected network. * - .. _cib_last_written: .. index:: pair: cib-last-written; cib cib-last-written - :ref:`date/time ` - - Indicates when the configuration was last written to disk. Maintained by the cluster; for informational purposes only. * - .. _have_quorum: .. index:: pair: have-quorum; cib have-quorum - :ref:`boolean ` - - Indicates whether the cluster has quorum. If false, the cluster's response is determined by ``no-quorum-policy`` (see below). Maintained by the cluster. * - .. _dc_uuid: .. index:: pair: dc-uuid; cib dc-uuid - :ref:`text ` - - Node ID of the cluster's current designated controller (DC). Used and maintained by the cluster. * - .. _execution_date: .. index:: pair: execution-date; cib execution-date - :ref:`epoch time ` - - Time to use when evaluating rules. .. _cluster_options: Cluster Options ############### Cluster options, as you might expect, control how the cluster behaves when confronted with various situations. They are grouped into sets within the ``crm_config`` section. In advanced configurations, there may be more than one set. (This will be described later in the chapter on :ref:`rules` where we will show how to have the cluster use different sets of options during working hours than during weekends.) For now, we will describe the simple case where each option is present at most once. You can obtain an up-to-date list of cluster options, including their default values, by running the ``man pacemaker-schedulerd`` and ``man pacemaker-controld`` commands. .. list-table:: **Cluster Options** :class: longtable - :widths: 2 2 2 5 + :widths: 25 13 12 50 :header-rows: 1 * - Name - Type - Default - Description * - .. _cluster_name: .. index:: pair: cluster option; cluster-name cluster-name - :ref:`text ` - - An (optional) name for the cluster as a whole. This is mostly for users' convenience for use as desired in administration, but can be used in the Pacemaker configuration in :ref:`rules` (as the ``#cluster-name`` :ref:`node attribute `). It may also be used by higher-level tools when displaying cluster information, and by certain resource agents (for example, the ``ocf:heartbeat:GFS2`` agent stores the cluster name in filesystem meta-data). * - .. _dc_version: .. index:: pair: cluster option; dc-version dc-version - :ref:`version ` - *detected* - Version of Pacemaker on the cluster's designated controller (DC). Maintained by the cluster, and intended for diagnostic purposes. * - .. _cluster_infrastructure: .. index:: pair: cluster option; cluster-infrastructure cluster-infrastructure - :ref:`text ` - *detected* - The messaging layer with which Pacemaker is currently running. Maintained by the cluster, and intended for informational and diagnostic purposes. * - .. _no_quorum_policy: .. index:: pair: cluster option; no-quorum-policy no-quorum-policy - :ref:`enumeration ` - stop - What to do when the cluster does not have quorum. Allowed values: * ``ignore:`` continue all resource management * ``freeze:`` continue resource management, but don't recover resources from nodes not in the affected partition * ``stop:`` stop all resources in the affected cluster partition * ``demote:`` demote promotable resources and stop all other resources in the affected cluster partition *(since 2.0.5)* * ``fence:`` fence all nodes in the affected cluster partition *(since 2.1.9)* * ``suicide:`` same as ``fence`` *(deprecated since 2.1.9)* * - .. _batch_limit: .. index:: pair: cluster option; batch-limit batch-limit - :ref:`integer ` - 0 - The maximum number of actions that the cluster may execute in parallel across all nodes. The ideal value will depend on the speed and load of your network and cluster nodes. If zero, the cluster will impose a dynamically calculated limit only when any node has high load. If -1, the cluster will not impose any limit. * - .. _migration_limit: .. index:: pair: cluster option; migration-limit migration-limit - :ref:`integer ` - -1 - The number of :ref:`live migration ` actions that the cluster is allowed to execute in parallel on a node. A value of -1 means unlimited. * - .. _load_threshold: .. index:: pair: cluster option; load-threshold load-threshold - :ref:`percentage ` - 80% - Maximum amount of system load that should be used by cluster nodes. The cluster will slow down its recovery process when the amount of system resources used (currently CPU) approaches this limit. * - .. _node_action_limit: .. index:: pair: cluster option; node-action-limit node-action-limit - :ref:`integer ` - 0 - Maximum number of jobs that can be scheduled per node. If nonpositive or invalid, double the number of cores is used as the maximum number of jobs per node. :ref:`PCMK_node_action_limit ` overrides this option on a per-node basis. * - .. _symmetric_cluster: .. index:: pair: cluster option; symmetric-cluster symmetric-cluster - :ref:`boolean ` - true - If true, resources can run on any node by default. If false, a resource is allowed to run on a node only if a :ref:`location constraint ` enables it. * - .. _stop_all_resources: .. index:: pair: cluster option; stop-all-resources stop-all-resources - :ref:`boolean ` - false - Whether all resources should be disallowed from running (can be useful during maintenance or troubleshooting) * - .. _stop_orphan_resources: .. index:: pair: cluster option; stop-orphan-resources stop-orphan-resources - :ref:`boolean ` - true - Whether resources that have been deleted from the configuration should be stopped. This value takes precedence over :ref:`is-managed ` (that is, even unmanaged resources will be stopped when orphaned if this value is ``true``). * - .. _stop_orphan_actions: .. index:: pair: cluster option; stop-orphan-actions stop-orphan-actions - :ref:`boolean ` - true - Whether recurring :ref:`operations ` that have been deleted from the configuration should be cancelled * - .. _start_failure_is_fatal: .. index:: pair: cluster option; start-failure-is-fatal start-failure-is-fatal - :ref:`boolean ` - true - Whether a failure to start a resource on a particular node prevents further start attempts on that node. If ``false``, the cluster will decide whether the node is still eligible based on the resource's current failure count and ``migration-threshold``. * - .. _enable_startup_probes: .. index:: pair: cluster option; enable-startup-probes enable-startup-probes - :ref:`boolean ` - true - Whether the cluster should check the pre-existing state of resources when the cluster starts * - .. _maintenance_mode: .. index:: pair: cluster option; maintenance-mode maintenance-mode - :ref:`boolean ` - false - If true, the cluster will not start or stop any resource in the cluster, and any recurring operations (expect those specifying ``role`` as ``Stopped``) will be paused. If true, this overrides the :ref:`maintenance ` node attribute, :ref:`is-managed ` and :ref:`maintenance ` resource meta-attributes, and :ref:`enabled ` operation meta-attribute. * - .. _stonith_enabled: .. index:: pair: cluster option; stonith-enabled stonith-enabled - :ref:`boolean ` - true - Whether the cluster is allowed to fence nodes (for example, failed nodes and nodes with resources that can't be stopped). If true, at least one fence device must be configured before resources are allowed to run. If false, unresponsive nodes are immediately assumed to be running no resources, and resource recovery on online nodes starts without any further protection (which can mean *data loss* if the unresponsive node still accesses shared storage, for example). See also the :ref:`requires ` resource meta-attribute. This option applies only to fencing scheduled by the cluster, not to requests initiated externally (such as with the ``stonith_admin`` command-line tool). * - .. _stonith_action: .. index:: pair: cluster option; stonith-action stonith-action - :ref:`enumeration ` - reboot - Action the cluster should send to the fence agent when a node must be fenced. Allowed values are ``reboot`` and ``off``. * - .. _stonith_timeout: .. index:: pair: cluster option; stonith-timeout stonith-timeout - :ref:`duration ` - 60s - How long to wait for ``on``, ``off``, and ``reboot`` fence actions to complete by default. * - .. _stonith_max_attempts: .. index:: pair: cluster option; stonith-max-attempts stonith-max-attempts - :ref:`score ` - 10 - How many times fencing can fail for a target before the cluster will no longer immediately re-attempt it. Any value below 1 will be ignored, and the default will be used instead. * - .. _have_watchdog: .. index:: pair: cluster option; have-watchdog have-watchdog - :ref:`boolean ` - *detected* - Whether watchdog integration is enabled. This is set automatically by the cluster according to whether SBD is detected to be in use. User-configured values are ignored. The value `true` is meaningful if diskless SBD is used and :ref:`stonith-watchdog-timeout ` is nonzero. In that case, if fencing is required, watchdog-based self-fencing will be performed via SBD without requiring a fencing resource explicitly configured. * - .. _stonith_watchdog_timeout: .. index:: pair: cluster option; stonith-watchdog-timeout stonith-watchdog-timeout - :ref:`timeout ` - 0 - If nonzero, and the cluster detects ``have-watchdog`` as ``true``, then watchdog-based self-fencing will be performed via SBD when fencing is required. If this is set to a positive value, lost nodes are assumed to achieve self-fencing within this much time. This does not require a fencing resource to be explicitly configured, though a fence_watchdog resource can be configured, to limit use to specific nodes. If this is set to 0 (the default), the cluster will never assume watchdog-based self-fencing. If this is set to a negative value, the cluster will use twice the local value of the ``SBD_WATCHDOG_TIMEOUT`` environment variable if that is positive, or otherwise treat this as 0. **Warning:** When used, this timeout must be larger than ``SBD_WATCHDOG_TIMEOUT`` on all nodes that use watchdog-based SBD, and Pacemaker will refuse to start on any of those nodes where this is not true for the local value or SBD is not active. When this is set to a negative value, ``SBD_WATCHDOG_TIMEOUT`` must be set to the same value on all nodes that use SBD, otherwise data corruption or loss could occur. * - .. _concurrent-fencing: .. index:: pair: cluster option; concurrent-fencing concurrent-fencing - :ref:`boolean ` - false - Whether the cluster is allowed to initiate multiple fence actions concurrently. Fence actions initiated externally, such as via the ``stonith_admin`` tool or an application such as DLM, or by the fencer itself such as recurring device monitors and ``status`` and ``list`` commands, are not limited by this option. * - .. _fence_reaction: .. index:: pair: cluster option; fence-reaction fence-reaction - :ref:`enumeration ` - stop - How should a cluster node react if notified of its own fencing? A cluster node may receive notification of a "succeeded" fencing that targeted it if fencing is misconfigured, or if fabric fencing is in use that doesn't cut cluster communication. Allowed values are ``stop`` to attempt to immediately stop Pacemaker and stay stopped, or ``panic`` to attempt to immediately reboot the local node, falling back to stop on failure. The default is likely to be changed to ``panic`` in a future release. *(since 2.0.3)* * - .. _priority_fencing_delay: .. index:: pair: cluster option; priority-fencing-delay priority-fencing-delay - :ref:`duration ` - 0 - Apply this delay to any fencing targeting the lost nodes with the highest total resource priority in case we don't have the majority of the nodes in our cluster partition, so that the more significant nodes potentially win any fencing match (especially meaningful in a split-brain of a 2-node cluster). A promoted resource instance takes the resource's priority plus 1 if the resource's priority is not 0. Any static or random delays introduced by ``pcmk_delay_base`` and ``pcmk_delay_max`` configured for the corresponding fencing resources will be added to this delay. This delay should be significantly greater than (safely twice) the maximum delay from those parameters. *(since 2.0.4)* * - .. _node_pending_timeout: .. index:: pair: cluster option; node-pending-timeout node-pending-timeout - :ref:`duration ` - 0 - Fence nodes that do not join the controller process group within this much time after joining the cluster, to allow the cluster to continue managing resources. A value of 0 means never fence pending nodes. Setting the value to 2h means fence nodes after 2 hours. *(since 2.1.7)* * - .. _cluster_delay: .. index:: pair: cluster option; cluster-delay cluster-delay - :ref:`duration ` - 60s - If the DC requires an action to be executed on another node, it will consider the action failed if it does not get a response from the other node within this time (beyond the action's own timeout). The ideal value will depend on the speed and load of your network and cluster nodes. * - .. _dc_deadtime: .. index:: pair: cluster option; dc-deadtime dc-deadtime - :ref:`duration ` - 20s - How long to wait for a response from other nodes when electing a DC. The ideal value will depend on the speed and load of your network and cluster nodes. * - .. _cluster_ipc_limit: .. index:: pair: cluster option; cluster-ipc-limit cluster-ipc-limit - :ref:`nonnegative integer ` - 500 - The maximum IPC message backlog before one cluster daemon will disconnect another. This is of use in large clusters, for which a good value is the number of resources in the cluster multiplied by the number of nodes. The default of 500 is also the minimum. Raise this if you see "Evicting client" log messages for cluster daemon process IDs. * - .. _pe_error_series_max: .. index:: pair: cluster option; pe-error-series-max pe-error-series-max - :ref:`integer ` - -1 - The number of scheduler inputs resulting in errors to save. These inputs can be helpful during troubleshooting and when reporting issues. A negative value means save all inputs, and 0 means save none. * - .. _pe_warn_series_max: .. index:: pair: cluster option; pe-warn-series-max pe-warn-series-max - :ref:`integer ` - 5000 - The number of scheduler inputs resulting in warnings to save. These inputs can be helpful during troubleshooting and when reporting issues. A negative value means save all inputs, and 0 means save none. * - .. _pe_input_series_max: .. index:: pair: cluster option; pe-input-series-max pe-input-series-max - :ref:`integer ` - 4000 - The number of "normal" scheduler inputs to save. These inputs can be helpful during troubleshooting and when reporting issues. A negative value means save all inputs, and 0 means save none. * - .. _enable_acl: .. index:: pair: cluster option; enable-acl enable-acl - :ref:`boolean ` - false - Whether :ref:`access control lists ` should be used to authorize CIB modifications * - .. _placement_strategy: .. index:: pair: cluster option; placement-strategy placement-strategy - :ref:`enumeration ` - default - How the cluster should assign resources to nodes (see :ref:`utilization`). Allowed values are ``default``, ``utilization``, ``balanced``, and ``minimal``. * - .. _node_health_strategy: .. index:: pair: cluster option; node-health-strategy node-health-strategy - :ref:`enumeration ` - none - How the cluster should react to :ref:`node health ` attributes. Allowed values are ``none``, ``migrate-on-red``, ``only-green``, ``progressive``, and ``custom``. * - .. _node_health_base: .. index:: pair: cluster option; node-health-base node-health-base - :ref:`score ` - 0 - The base health score assigned to a node. Only used when ``node-health-strategy`` is ``progressive``. * - .. _node_health_green: .. index:: pair: cluster option; node-health-green node-health-green - :ref:`score ` - 0 - The score to use for a node health attribute whose value is ``green``. Only used when ``node-health-strategy`` is ``progressive`` or ``custom``. * - .. _node_health_yellow: .. index:: pair: cluster option; node-health-yellow node-health-yellow - :ref:`score ` - 0 - The score to use for a node health attribute whose value is ``yellow``. Only used when ``node-health-strategy`` is ``progressive`` or ``custom``. * - .. _node_health_red: .. index:: pair: cluster option; node-health-red node-health-red - :ref:`score ` - -INFINITY - The score to use for a node health attribute whose value is ``red``. Only used when ``node-health-strategy`` is ``progressive`` or ``custom``. * - .. _cluster_recheck_interval: .. index:: pair: cluster option; cluster-recheck-interval cluster-recheck-interval - :ref:`duration ` - 15min - Pacemaker is primarily event-driven, and looks ahead to know when to recheck the cluster for failure-timeout settings and most time-based rules *(since 2.0.3)*. However, it will also recheck the cluster after this amount of inactivity. This has three main effects: * :ref:`Rules ` using ``date_spec`` are guaranteed to be checked only this often. * If :ref:`fencing ` fails enough to reach :ref:`stonith-max-attempts `, attempts will begin again after at most this time. * It serves as a fail-safe in case of certain scheduler bugs. If the scheduler incorrectly determines only some of the actions needed to react to a particular event, it will often correctly determine the rest after at most this time. A value of 0 disables this polling. * - .. _shutdown_lock: .. index:: pair: cluster option; shutdown-lock shutdown-lock - :ref:`boolean ` - false - The default of false allows active resources to be recovered elsewhere when their node is cleanly shut down, which is what the vast majority of users will want. However, some users prefer to make resources highly available only for failures, with no recovery for clean shutdowns. If this option is true, resources active on a node when it is cleanly shut down are kept "locked" to that node (not allowed to run elsewhere) until they start again on that node after it rejoins (or for at most ``shutdown-lock-limit``, if set). Stonith resources and Pacemaker Remote connections are never locked. Clone and bundle instances and the promoted role of promotable clones are currently never locked, though support could be added in a future release. Locks may be manually cleared using the ``--refresh`` option of ``crm_resource`` (both the resource and node must be specified; this works with remote nodes if their connection resource's ``target-role`` is set to ``Stopped``, but not if Pacemaker Remote is stopped on the remote node without disabling the connection resource). *(since 2.0.4)* * - .. _shutdown_lock_limit: .. index:: pair: cluster option; shutdown-lock-limit shutdown-lock-limit - :ref:`duration ` - 0 - If ``shutdown-lock`` is true, and this is set to a nonzero time duration, locked resources will be allowed to start after this much time has passed since the node shutdown was initiated, even if the node has not rejoined. (This works with remote nodes only if their connection resource's ``target-role`` is set to ``Stopped``.) *(since 2.0.4)* * - .. _startup_fencing: .. index:: pair: cluster option; startup-fencing startup-fencing - :ref:`boolean ` - true - *Advanced Use Only:* Whether the cluster should fence unseen nodes at start-up. Setting this to false is unsafe, because the unseen nodes could be active and running resources but unreachable. ``dc-deadtime`` acts as a grace period before this fencing, since a DC must be elected to schedule fencing. * - .. _election_timeout: .. index:: pair: cluster option; election-timeout election-timeout - :ref:`duration ` - 2min - *Advanced Use Only:* If a winner is not declared within this much time of starting an election, the node that initiated the election will declare itself the winner. * - .. _shutdown_escalation: .. index:: pair: cluster option; shutdown-escalation shutdown-escalation - :ref:`duration ` - 20min - *Advanced Use Only:* The controller will exit immediately if a shutdown does not complete within this much time. * - .. _join_integration_timeout: .. index:: pair: cluster option; join-integration-timeout join-integration-timeout - :ref:`duration ` - 3min - *Advanced Use Only:* If you need to adjust this value, it probably indicates the presence of a bug. * - .. _join_finalization_timeout: .. index:: pair: cluster option; join-finalization-timeout join-finalization-timeout - :ref:`duration ` - 30min - *Advanced Use Only:* If you need to adjust this value, it probably indicates the presence of a bug. * - .. _transition_delay: .. index:: pair: cluster option; transition-delay transition-delay - :ref:`duration ` - 0s - *Advanced Use Only:* Delay cluster recovery for the configured interval to allow for additional or related events to occur. This can be useful if your configuration is sensitive to the order in which ping updates arrive. Enabling this option will slow down cluster recovery under all conditions. diff --git a/doc/sphinx/Pacemaker_Explained/collective.rst b/doc/sphinx/Pacemaker_Explained/collective.rst index 73fb7a7e4a..d86caf8d2d 100644 --- a/doc/sphinx/Pacemaker_Explained/collective.rst +++ b/doc/sphinx/Pacemaker_Explained/collective.rst @@ -1,1193 +1,1193 @@ .. index: single: collective resource single: resource; collective Collective Resources -------------------- Pacemaker supports several types of *collective* resources, which consist of multiple, related resource instances. .. index: single: group resource single: resource; group .. _group-resources: Groups - A Syntactic Shortcut ############################# One of the most common elements of a cluster is a set of resources that need to be located together, start sequentially, and stop in the reverse order. To simplify this configuration, we support the concept of groups. .. topic:: A group of two primitive resources .. code-block:: xml Although the example above contains only two resources, there is no limit to the number of resources a group can contain. The example is also sufficient to explain the fundamental properties of a group: * Resources are started in the order they appear in (**Public-IP** first, then **Email**) * Resources are stopped in the reverse order to which they appear in (**Email** first, then **Public-IP**) If a resource in the group can't run anywhere, then nothing after that is allowed to run, too. * If **Public-IP** can't run anywhere, neither can **Email**; * but if **Email** can't run anywhere, this does not affect **Public-IP** in any way The group above is logically equivalent to writing: .. topic:: How the cluster sees a group resource .. code-block:: xml Obviously as the group grows bigger, the reduced configuration effort can become significant. Another (typical) example of a group is a DRBD volume, the filesystem mount, an IP address, and an application that uses them. .. index:: pair: XML element; group Group Properties ________________ .. table:: **Properties of a Group Resource** - :widths: 1 4 + :widths: 25 75 +-------------+------------------------------------------------------------------+ | Field | Description | +=============+==================================================================+ | id | .. index:: | | | single: group; property, id | | | single: property; id (group) | | | single: id; group property | | | | | | A unique name for the group | +-------------+------------------------------------------------------------------+ | description | .. index:: | | | single: group; attribute, description | | | single: attribute; description (group) | | | single: description; group attribute | | | | | | Arbitrary text for user's use (ignored by Pacemaker) | +-------------+------------------------------------------------------------------+ Group Options _____________ Groups inherit the ``priority``, ``target-role``, and ``is-managed`` properties from primitive resources. See :ref:`resource_options` for information about those properties. Group Instance Attributes _________________________ Groups have no instance attributes. However, any that are set for the group object will be inherited by the group's children. Group Contents ______________ Groups may only contain a collection of cluster resources (see :ref:`primitive-resource`). To refer to a child of a group resource, just use the child's ``id`` instead of the group's. Group Constraints _________________ Although it is possible to reference a group's children in constraints, it is usually preferable to reference the group itself. .. topic:: Some constraints involving groups .. code-block:: xml .. index:: pair: resource-stickiness; group Group Stickiness ________________ Stickiness, the measure of how much a resource wants to stay where it is, is additive in groups. Every active resource of the group will contribute its stickiness value to the group's total. So if the default ``resource-stickiness`` is 100, and a group has seven members, five of which are active, then the group as a whole will prefer its current location with a score of 500. .. index:: single: clone single: resource; clone .. _s-resource-clone: Clones - Resources That Can Have Multiple Active Instances ########################################################## *Clone* resources are resources that can have more than one copy active at the same time. This allows you, for example, to run a copy of a daemon on every node. You can clone any primitive or group resource [#]_. Anonymous versus Unique Clones ______________________________ A clone resource is configured to be either *anonymous* or *globally unique*. Anonymous clones are the simplest. These behave completely identically everywhere they are running. Because of this, there can be only one instance of an anonymous clone active per node. The instances of globally unique clones are distinct entities. All instances are launched identically, but one instance of the clone is not identical to any other instance, whether running on the same node or a different node. As an example, a cloned IP address can use special kernel functionality such that each instance handles a subset of requests for the same IP address. .. index:: single: promotable clone single: resource; promotable .. _s-resource-promotable: Promotable clones _________________ If a clone is *promotable*, its instances can perform a special role that Pacemaker will manage via the ``promote`` and ``demote`` actions of the resource agent. Services that support such a special role have various terms for the special role and the default role: primary and secondary, master and replica, controller and worker, etc. Pacemaker uses the terms *promoted* and *unpromoted* to be agnostic to what the service calls them or what they do. All that Pacemaker cares about is that an instance comes up in the unpromoted role when started, and the resource agent supports the ``promote`` and ``demote`` actions to manage entering and exiting the promoted role. .. index:: pair: XML element; clone Clone Properties ________________ .. table:: **Properties of a Clone Resource** - :widths: 1 4 + :widths: 25 75 +-------------+------------------------------------------------------------------+ | Field | Description | +=============+==================================================================+ | id | .. index:: | | | single: clone; property, id | | | single: property; id (clone) | | | single: id; clone property | | | | | | A unique name for the clone | +-------------+------------------------------------------------------------------+ | description | .. index:: | | | single: clone; attribute, description | | | single: attribute; description (clone) | | | single: description; clone attribute | | | | | | Arbitrary text for user's use (ignored by Pacemaker) | +-------------+------------------------------------------------------------------+ .. index:: pair: options; clone Clone Options _____________ :ref:`Options ` inherited from primitive resources: ``priority, target-role, is-managed`` .. table:: **Clone-specific configuration options** :class: longtable - :widths: 1 1 3 + :widths: 20 20 60 +-------------------+-----------------+-------------------------------------------------------+ | Field | Default | Description | +===================+=================+=======================================================+ | globally-unique | **true** if | .. index:: | | | clone-node-max | single: clone; option, globally-unique | | | is greater than | single: option; globally-unique (clone) | | | 1 *(since* | single: globally-unique; clone option | | | *3.0.0)*, | | | | otherwise | If **true**, each clone instance performs a | | | **false** | distinct function, such that a single node can run | | | | more than one instance at the same time | +-------------------+-----------------+-------------------------------------------------------+ | clone-max | 0 | .. index:: | | | | single: clone; option, clone-max | | | | single: option; clone-max (clone) | | | | single: clone-max; clone option | | | | | | | | The maximum number of clone instances that can | | | | be started across the entire cluster. If 0, the | | | | number of nodes in the cluster will be used. | +-------------------+-----------------+-------------------------------------------------------+ | clone-node-max | 1 | .. index:: | | | | single: clone; option, clone-node-max | | | | single: option; clone-node-max (clone) | | | | single: clone-node-max; clone option | | | | | | | | If the clone is globally unique, this is the maximum | | | | number of clone instances that can be started | | | | on a single node | +-------------------+-----------------+-------------------------------------------------------+ | clone-min | 0 | .. index:: | | | | single: clone; option, clone-min | | | | single: option; clone-min (clone) | | | | single: clone-min; clone option | | | | | | | | Require at least this number of clone instances | | | | to be runnable before allowing resources | | | | depending on the clone to be runnable. A value | | | | of 0 means require all clone instances to be | | | | runnable. | +-------------------+-----------------+-------------------------------------------------------+ | notify | false | .. index:: | | | | single: clone; option, notify | | | | single: option; notify (clone) | | | | single: notify; clone option | | | | | | | | Call the resource agent's **notify** action for | | | | all active instances, before and after starting | | | | or stopping any clone instance. The resource | | | | agent must support this action. | | | | Allowed values: **false**, **true** | +-------------------+-----------------+-------------------------------------------------------+ | ordered | false | .. index:: | | | | single: clone; option, ordered | | | | single: option; ordered (clone) | | | | single: ordered; clone option | | | | | | | | If **true**, clone instances must be started | | | | sequentially instead of in parallel. | | | | Allowed values: **false**, **true** | +-------------------+-----------------+-------------------------------------------------------+ | interleave | false | .. index:: | | | | single: clone; option, interleave | | | | single: option; interleave (clone) | | | | single: interleave; clone option | | | | | | | | When this clone is ordered relative to another | | | | clone, if this option is **false** (the default), | | | | the ordering is relative to *all* instances of | | | | the other clone, whereas if this option is | | | | **true**, the ordering is relative only to | | | | instances on the same node. | | | | Allowed values: **false**, **true** | +-------------------+-----------------+-------------------------------------------------------+ | promotable | false | .. index:: | | | | single: clone; option, promotable | | | | single: option; promotable (clone) | | | | single: promotable; clone option | | | | | | | | If **true**, clone instances can perform a | | | | special role that Pacemaker will manage via the | | | | resource agent's **promote** and **demote** | | | | actions. The resource agent must support these | | | | actions. | | | | Allowed values: **false**, **true** | +-------------------+-----------------+-------------------------------------------------------+ | promoted-max | 1 | .. index:: | | | | single: clone; option, promoted-max | | | | single: option; promoted-max (clone) | | | | single: promoted-max; clone option | | | | | | | | If ``promotable`` is **true**, the number of | | | | instances that can be promoted at one time | | | | across the entire cluster | +-------------------+-----------------+-------------------------------------------------------+ | promoted-node-max | 1 | .. index:: | | | | single: clone; option, promoted-node-max | | | | single: option; promoted-node-max (clone) | | | | single: promoted-node-max; clone option | | | | | | | | If the clone is promotable and globally unique, this | | | | is the number of instances that can be promoted at | | | | one time on a single node (up to ``clone-node-max``) | +-------------------+-----------------+-------------------------------------------------------+ .. note:: **Deprecated Terminology** In older documentation and online examples, you may see promotable clones referred to as *multi-state*, *stateful*, or *master/slave*; these mean the same thing as *promotable*. Certain syntax is supported for backward compatibility, but is deprecated and will be removed in a future version: * Using the ``master-max`` meta-attribute instead of ``promoted-max`` * Using the ``master-node-max`` meta-attribute instead of ``promoted-node-max`` * Using ``Master`` as a role name instead of ``Promoted`` * Using ``Slave`` as a role name instead of ``Unpromoted`` Clone Contents ______________ Clones must contain exactly one primitive or group resource. .. topic:: A clone that runs a web server on all nodes .. code-block:: xml .. warning:: You should never reference the name of a clone's child (the primitive or group resource being cloned). If you think you need to do this, you probably need to re-evaluate your design. Clone Instance Attribute ________________________ Clones have no instance attributes; however, any that are set here will be inherited by the clone's child. .. index:: single: clone; constraint Clone Constraints _________________ In most cases, a clone will have a single instance on each active cluster node. If this is not the case, you can indicate which nodes the cluster should preferentially assign copies to with resource location constraints. These constraints are written no differently from those for primitive resources except that the clone's **id** is used. .. topic:: Some constraints involving clones .. code-block:: xml Ordering constraints behave slightly differently for clones. In the example above, ``apache-stats`` will wait until all copies of ``apache-clone`` that need to be started have done so before being started itself. Only if *no* copies can be started will ``apache-stats`` be prevented from being active. Additionally, the clone will wait for ``apache-stats`` to be stopped before stopping itself. Colocation of a primitive or group resource with a clone means that the resource can run on any node with an active instance of the clone. The cluster will choose an instance based on where the clone is running and the resource's own location preferences. Colocation between clones is also possible. If one clone **A** is colocated with another clone **B**, the set of allowed locations for **A** is limited to nodes on which **B** is (or will be) active. Placement is then performed normally. .. index:: single: promotable clone; constraint .. _promotable-clone-constraints: Promotable Clone Constraints ~~~~~~~~~~~~~~~~~~~~~~~~~~~~ For promotable clone resources, the ``first-action`` and/or ``then-action`` fields for ordering constraints may be set to ``promote`` or ``demote`` to constrain the promoted role, and colocation constraints may contain ``rsc-role`` and/or ``with-rsc-role`` fields. .. topic:: Constraints involving promotable clone resources .. code-block:: xml In the example above, **myApp** will wait until one of the database copies has been started and promoted before being started itself on the same node. Only if no copies can be promoted will **myApp** be prevented from being active. Additionally, the cluster will wait for **myApp** to be stopped before demoting the database. Colocation of a primitive or group resource with a promotable clone resource means that it can run on any node with an active instance of the promotable clone resource that has the specified role (``Promoted`` or ``Unpromoted``). In the example above, the cluster will choose a location based on where database is running in the promoted role, and if there are multiple promoted instances it will also factor in **myApp**'s own location preferences when deciding which location to choose. Colocation with regular clones and other promotable clone resources is also possible. In such cases, the set of allowed locations for the **rsc** clone is (after role filtering) limited to nodes on which the ``with-rsc`` promotable clone resource is (or will be) in the specified role. Placement is then performed as normal. Using Promotable Clone Resources in Colocation Sets ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ When a promotable clone is used in a :ref:`resource set ` inside a colocation constraint, the resource set may take a ``role`` attribute. In the following example, an instance of **B** may be promoted only on a node where **A** is in the promoted role. Additionally, resources **C** and **D** must be located on a node where both **A** and **B** are promoted. .. topic:: Colocate C and D with A's and B's promoted instances .. code-block:: xml Using Promotable Clone Resources in Ordered Sets ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ When a promotable clone is used in a :ref:`resource set ` inside an ordering constraint, the resource set may take an ``action`` attribute. .. topic:: Start C and D after first promoting A and B .. code-block:: xml In the above example, **B** cannot be promoted until **A** has been promoted. Additionally, resources **C** and **D** must wait until **A** and **B** have been promoted before they can start. .. index:: pair: resource-stickiness; clone .. _s-clone-stickiness: Clone Stickiness ________________ To achieve stable assignments, clones are slightly sticky by default. If no value for ``resource-stickiness`` is provided, the clone will use a value of 1. Being a small value, it causes minimal disturbance to the score calculations of other resources but is enough to prevent Pacemaker from needlessly moving instances around the cluster. .. note:: For globally unique clones, this may result in multiple instances of the clone staying on a single node, even after another eligible node becomes active (for example, after being put into standby mode then made active again). If you do not want this behavior, specify a ``resource-stickiness`` of 0 for the clone temporarily and let the cluster adjust, then set it back to 1 if you want the default behavior to apply again. .. important:: If ``resource-stickiness`` is set in the ``rsc_defaults`` section, it will apply to clone instances as well. This means an explicit ``resource-stickiness`` of 0 in ``rsc_defaults`` works differently from the implicit default used when ``resource-stickiness`` is not specified. Monitoring Promotable Clone Resources _____________________________________ The usual monitor actions are insufficient to monitor a promotable clone resource, because Pacemaker needs to verify not only that the resource is active, but also that its actual role matches its intended one. Define two monitoring actions: the usual one will cover the unpromoted role, and an additional one with ``role="Promoted"`` will cover the promoted role. .. topic:: Monitoring both states of a promotable clone resource .. code-block:: xml .. important:: It is crucial that *every* monitor operation has a different interval! Pacemaker currently differentiates between operations only by resource and interval; so if (for example) a promotable clone resource had the same monitor interval for both roles, Pacemaker would ignore the role when checking the status -- which would cause unexpected return codes, and therefore unnecessary complications. .. _s-promotion-scores: Determining Which Instance is Promoted ______________________________________ Pacemaker can choose a promotable clone instance to be promoted in one of two ways: * Promotion scores: These are node attributes set via the ``crm_attribute`` command using the ``--promotion`` option, which generally would be called by the resource agent's start action if it supports promotable clones. This tool automatically detects both the resource and host, and should be used to set a preference for being promoted. Based on this, ``promoted-max``, and ``promoted-node-max``, the instance(s) with the highest preference will be promoted. * Constraints: Location constraints can indicate which nodes are most preferred to be promoted. .. topic:: Explicitly preferring node1 to be promoted .. code-block:: xml .. index: single: bundle single: resource; bundle pair: container; Docker pair: container; podman .. _s-resource-bundle: Bundles - Containerized Resources ################################# Pacemaker supports a special syntax for launching a service inside a `container `_ with any infrastructure it requires: the *bundle*. Pacemaker bundles support `Docker `_ and `podman `_ *(since 2.0.1)* container technologies. [#]_ .. topic:: A bundle for a containerized web server .. code-block:: xml Bundle Prerequisites ____________________ Before configuring a bundle in Pacemaker, the user must install the appropriate container launch technology (Docker or podman), and supply a fully configured container image, on every node allowed to run the bundle. Pacemaker will create an implicit resource of type **ocf:heartbeat:docker** or **ocf:heartbeat:podman** to manage a bundle's container. The user must ensure that the appropriate resource agent is installed on every node allowed to run the bundle. .. index:: pair: XML element; bundle Bundle Properties _________________ .. table:: **XML Attributes of a bundle Element** - :widths: 1 4 + :widths: 25 75 +-------------+------------------------------------------------------------------+ | Field | Description | +=============+==================================================================+ | id | .. index:: | | | single: bundle; attribute, id | | | single: attribute; id (bundle) | | | single: id; bundle attribute | | | | | | A unique name for the bundle (required) | +-------------+------------------------------------------------------------------+ | description | .. index:: | | | single: bundle; attribute, description | | | single: attribute; description (bundle) | | | single: description; bundle attribute | | | | | | Arbitrary text for user's use (ignored by Pacemaker) | +-------------+------------------------------------------------------------------+ A bundle must contain exactly one ``docker`` or ``podman`` element. .. index:: pair: XML element; docker pair: XML element; podman Bundle Container Properties ___________________________ .. table:: **XML attributes of a docker or podman Element** :class: longtable - :widths: 2 3 4 + :widths: 15 40 45 +-------------------+------------------------------------+---------------------------------------------------+ | Attribute | Default | Description | +===================+====================================+===================================================+ | image | | .. index:: | | | | single: docker; attribute, image | | | | single: attribute; image (docker) | | | | single: image; docker attribute | | | | single: podman; attribute, image | | | | single: attribute; image (podman) | | | | single: image; podman attribute | | | | | | | | Container image tag (required) | +-------------------+------------------------------------+---------------------------------------------------+ | replicas | Value of ``promoted-max`` | .. index:: | | | if that is positive, else 1 | single: docker; attribute, replicas | | | | single: attribute; replicas (docker) | | | | single: replicas; docker attribute | | | | single: podman; attribute, replicas | | | | single: attribute; replicas (podman) | | | | single: replicas; podman attribute | | | | | | | | A positive integer specifying the number of | | | | container instances to launch | +-------------------+------------------------------------+---------------------------------------------------+ | replicas-per-host | 1 | .. index:: | | | | single: docker; attribute, replicas-per-host | | | | single: attribute; replicas-per-host (docker) | | | | single: replicas-per-host; docker attribute | | | | single: podman; attribute, replicas-per-host | | | | single: attribute; replicas-per-host (podman) | | | | single: replicas-per-host; podman attribute | | | | | | | | A positive integer specifying the number of | | | | container instances allowed to run on a | | | | single node | +-------------------+------------------------------------+---------------------------------------------------+ | promoted-max | 0 | .. index:: | | | | single: docker; attribute, promoted-max | | | | single: attribute; promoted-max (docker) | | | | single: promoted-max; docker attribute | | | | single: podman; attribute, promoted-max | | | | single: attribute; promoted-max (podman) | | | | single: promoted-max; podman attribute | | | | | | | | A non-negative integer that, if positive, | | | | indicates that the containerized service | | | | should be treated as a promotable service, | | | | with this many replicas allowed to run the | | | | service in the promoted role | +-------------------+------------------------------------+---------------------------------------------------+ | network | | .. index:: | | | | single: docker; attribute, network | | | | single: attribute; network (docker) | | | | single: network; docker attribute | | | | single: podman; attribute, network | | | | single: attribute; network (podman) | | | | single: network; podman attribute | | | | | | | | If specified, this will be passed to the | | | | ``docker run`` or ``podman run`` command as the | | | | network setting for the container. | +-------------------+------------------------------------+---------------------------------------------------+ | run-command | ``/usr/sbin/pacemaker-remoted`` if | .. index:: | | | bundle contains a **primitive**, | single: docker; attribute, run-command | | | otherwise none | single: attribute; run-command (docker) | | | | single: run-command; docker attribute | | | | single: podman; attribute, run-command | | | | single: attribute; run-command (podman) | | | | single: run-command; podman attribute | | | | | | | | This command will be run inside the container | | | | when launching it ("PID 1"). If the bundle | | | | contains a **primitive**, this command *must* | | | | start ``pacemaker-remoted`` (but could, for | | | | example, be a script that does other stuff, too). | +-------------------+------------------------------------+---------------------------------------------------+ | options | | .. index:: | | | | single: docker; attribute, options | | | | single: attribute; options (docker) | | | | single: options; docker attribute | | | | single: podman; attribute, options | | | | single: attribute; options (podman) | | | | single: options; podman attribute | | | | | | | | Extra command-line options to pass to the | | | | ``docker run`` or ``podman run`` command | +-------------------+------------------------------------+---------------------------------------------------+ .. note:: Considerations when using cluster configurations or container images from Pacemaker 1.1: * If the container image has a pre-2.0.0 version of Pacemaker, set ``run-command`` to ``/usr/sbin/pacemaker_remoted`` (note the underbar instead of dash). * ``masters`` is accepted as an alias for ``promoted-max``, but is deprecated since 2.0.0, and support for it will be removed in a future version. Bundle Network Properties _________________________ A bundle may optionally contain one ```` element. .. index:: pair: XML element; network single: bundle; network .. table:: **XML attributes of a network Element** - :widths: 2 1 5 + :widths: 20 20 60 +----------------+---------+------------------------------------------------------------+ | Attribute | Default | Description | +================+=========+============================================================+ | add-host | TRUE | .. index:: | | | | single: network; attribute, add-host | | | | single: attribute; add-host (network) | | | | single: add-host; network attribute | | | | | | | | If TRUE, and ``ip-range-start`` is used, Pacemaker will | | | | automatically ensure that ``/etc/hosts`` inside the | | | | containers has entries for each | | | | :ref:`replica name ` | | | | and its assigned IP. | +----------------+---------+------------------------------------------------------------+ | ip-range-start | | .. index:: | | | | single: network; attribute, ip-range-start | | | | single: attribute; ip-range-start (network) | | | | single: ip-range-start; network attribute | | | | | | | | If specified, Pacemaker will create an implicit | | | | ``ocf:heartbeat:IPaddr2`` resource for each container | | | | instance, starting with this IP address, using up to | | | | ``replicas`` sequential addresses. These addresses can be | | | | used from the host's network to reach the service inside | | | | the container, though it is not visible within the | | | | container itself. Only IPv4 addresses are currently | | | | supported. | +----------------+---------+------------------------------------------------------------+ | host-netmask | 32 | .. index:: | | | | single: network; attribute; host-netmask | | | | single: attribute; host-netmask (network) | | | | single: host-netmask; network attribute | | | | | | | | If ``ip-range-start`` is specified, the IP addresses | | | | are created with this CIDR netmask (as a number of bits). | +----------------+---------+------------------------------------------------------------+ | host-interface | | .. index:: | | | | single: network; attribute; host-interface | | | | single: attribute; host-interface (network) | | | | single: host-interface; network attribute | | | | | | | | If ``ip-range-start`` is specified, the IP addresses are | | | | created on this host interface (by default, it will be | | | | determined from the IP address). | +----------------+---------+------------------------------------------------------------+ | control-port | 3121 | .. index:: | | | | single: network; attribute; control-port | | | | single: attribute; control-port (network) | | | | single: control-port; network attribute | | | | | | | | If the bundle contains a ``primitive``, the cluster will | | | | use this integer TCP port for communication with | | | | Pacemaker Remote inside the container. Changing this is | | | | useful when the container is unable to listen on the | | | | default port, for example, when the container uses the | | | | host's network rather than ``ip-range-start`` (in which | | | | case ``replicas-per-host`` must be 1), or when the bundle | | | | may run on a Pacemaker Remote node that is already | | | | listening on the default port. Any ``PCMK_remote_port`` | | | | environment variable set on the host or in the container | | | | is ignored for bundle connections. | +----------------+---------+------------------------------------------------------------+ .. _s-resource-bundle-note-replica-names: .. note:: Replicas are named by the bundle id plus a dash and an integer counter starting with zero. For example, if a bundle named **httpd-bundle** has **replicas=2**, its containers will be named **httpd-bundle-0** and **httpd-bundle-1**. .. index:: pair: XML element; port-mapping Additionally, a ``network`` element may optionally contain one or more ``port-mapping`` elements. .. table:: **Attributes of a port-mapping Element** - :widths: 2 1 5 + :widths: 20 20 60 +---------------+-------------------+------------------------------------------------------+ | Attribute | Default | Description | +===============+===================+======================================================+ | id | | .. index:: | | | | single: port-mapping; attribute, id | | | | single: attribute; id (port-mapping) | | | | single: id; port-mapping attribute | | | | | | | | A unique name for the port mapping (required) | +---------------+-------------------+------------------------------------------------------+ | port | | .. index:: | | | | single: port-mapping; attribute, port | | | | single: attribute; port (port-mapping) | | | | single: port; port-mapping attribute | | | | | | | | If this is specified, connections to this TCP port | | | | number on the host network (on the container's | | | | assigned IP address, if ``ip-range-start`` is | | | | specified) will be forwarded to the container | | | | network. Exactly one of ``port`` or ``range`` | | | | must be specified in a ``port-mapping``. | +---------------+-------------------+------------------------------------------------------+ | internal-port | value of ``port`` | .. index:: | | | | single: port-mapping; attribute, internal-port | | | | single: attribute; internal-port (port-mapping) | | | | single: internal-port; port-mapping attribute | | | | | | | | If ``port`` and this are specified, connections | | | | to ``port`` on the host's network will be | | | | forwarded to this port on the container network. | +---------------+-------------------+------------------------------------------------------+ | range | | .. index:: | | | | single: port-mapping; attribute, range | | | | single: attribute; range (port-mapping) | | | | single: range; port-mapping attribute | | | | | | | | If this is specified, connections to these TCP | | | | port numbers (expressed as *first_port*-*last_port*) | | | | on the host network (on the container's assigned IP | | | | address, if ``ip-range-start`` is specified) will | | | | be forwarded to the same ports in the container | | | | network. Exactly one of ``port`` or ``range`` | | | | must be specified in a ``port-mapping``. | +---------------+-------------------+------------------------------------------------------+ .. note:: If the bundle contains a ``primitive``, Pacemaker will automatically map the ``control-port``, so it is not necessary to specify that port in a ``port-mapping``. .. index: pair: XML element; storage pair: XML element; storage-mapping single: bundle; storage .. _s-bundle-storage: Bundle Storage Properties _________________________ A bundle may optionally contain one ``storage`` element. A ``storage`` element has no properties of its own, but may contain one or more ``storage-mapping`` elements. .. table:: **Attributes of a storage-mapping Element** - :widths: 2 1 5 + :widths: 20 20 60 +-----------------+---------+-------------------------------------------------------------+ | Attribute | Default | Description | +=================+=========+=============================================================+ | id | | .. index:: | | | | single: storage-mapping; attribute, id | | | | single: attribute; id (storage-mapping) | | | | single: id; storage-mapping attribute | | | | | | | | A unique name for the storage mapping (required) | +-----------------+---------+-------------------------------------------------------------+ | source-dir | | .. index:: | | | | single: storage-mapping; attribute, source-dir | | | | single: attribute; source-dir (storage-mapping) | | | | single: source-dir; storage-mapping attribute | | | | | | | | The absolute path on the host's filesystem that will be | | | | mapped into the container. Exactly one of ``source-dir`` | | | | and ``source-dir-root`` must be specified in a | | | | ``storage-mapping``. | +-----------------+---------+-------------------------------------------------------------+ | source-dir-root | | .. index:: | | | | single: storage-mapping; attribute, source-dir-root | | | | single: attribute; source-dir-root (storage-mapping) | | | | single: source-dir-root; storage-mapping attribute | | | | | | | | The start of a path on the host's filesystem that will | | | | be mapped into the container, using a different | | | | subdirectory on the host for each container instance. | | | | The subdirectory will be named the same as the | | | | :ref:`replica name `. | | | | Exactly one of ``source-dir`` and ``source-dir-root`` | | | | must be specified in a ``storage-mapping``. | +-----------------+---------+-------------------------------------------------------------+ | target-dir | | .. index:: | | | | single: storage-mapping; attribute, target-dir | | | | single: attribute; target-dir (storage-mapping) | | | | single: target-dir; storage-mapping attribute | | | | | | | | The path name within the container where the host | | | | storage will be mapped (required) | +-----------------+---------+-------------------------------------------------------------+ | options | | .. index:: | | | | single: storage-mapping; attribute, options | | | | single: attribute; options (storage-mapping) | | | | single: options; storage-mapping attribute | | | | | | | | A comma-separated list of file system mount | | | | options to use when mapping the storage | +-----------------+---------+-------------------------------------------------------------+ .. note:: Pacemaker does not define the behavior if the source directory does not already exist on the host. However, it is expected that the container technology and/or its resource agent will create the source directory in that case. .. note:: If the bundle contains a ``primitive``, Pacemaker will automatically map the equivalent of ``source-dir=/etc/pacemaker/authkey target-dir=/etc/pacemaker/authkey`` and ``source-dir-root=/var/log/pacemaker/bundles target-dir=/var/log`` into the container, so it is not necessary to specify those paths in a ``storage-mapping``. .. important:: The ``PCMK_authkey_location`` environment variable must not be set to anything other than the default of ``/etc/pacemaker/authkey`` on any node in the cluster. .. important:: If SELinux is used in enforcing mode on the host, you must ensure the container is allowed to use any storage you mount into it. For Docker and podman bundles, adding "Z" to the mount options will create a container-specific label for the mount that allows the container access. .. index:: single: bundle; primitive Bundle Primitive ________________ A bundle may optionally contain one :ref:`primitive ` resource. The primitive may have operations, instance attributes, and meta-attributes defined, as usual. If a bundle contains a primitive resource, the container image must include the Pacemaker Remote daemon, and at least one of ``ip-range-start`` or ``control-port`` must be configured in the bundle. Pacemaker will create an implicit **ocf:pacemaker:remote** resource for the connection, launch Pacemaker Remote within the container, and monitor and manage the primitive resource via Pacemaker Remote. If the bundle has more than one container instance (replica), the primitive resource will function as an implicit :ref:`clone ` -- a :ref:`promotable clone ` if the bundle has ``promoted-max`` greater than zero. .. note:: If you want to pass environment variables to a bundle's Pacemaker Remote connection or primitive, you have two options: * Environment variables whose value is the same regardless of the underlying host may be set using the container element's ``options`` attribute. * If you want variables to have host-specific values, you can use the :ref:`storage-mapping ` element to map a file on the host as ``/etc/pacemaker/pcmk-init.env`` in the container *(since 2.0.3)*. Pacemaker Remote will parse this file as a shell-like format, with variables set as NAME=VALUE, ignoring blank lines and comments starting with "#". .. important:: When a bundle has a ``primitive``, Pacemaker on all cluster nodes must be able to contact Pacemaker Remote inside the bundle's containers. * The containers must have an accessible network (for example, ``network`` should not be set to "none" with a ``primitive``). * The default, using a distinct network space inside the container, works in combination with ``ip-range-start``. Any firewall must allow access from all cluster nodes to the ``control-port`` on the container IPs. * If the container shares the host's network space (for example, by setting ``network`` to "host"), a unique ``control-port`` should be specified for each bundle. Any firewall must allow access from all cluster nodes to the ``control-port`` on all cluster and remote node IPs. .. index:: single: bundle; node attributes .. _s-bundle-attributes: Bundle Node Attributes ______________________ If the bundle has a ``primitive``, the primitive's resource agent may want to set node attributes such as :ref:`promotion scores `. However, with containers, it is not apparent which node should get the attribute. If the container uses shared storage that is the same no matter which node the container is hosted on, then it is appropriate to use the promotion score on the bundle node itself. On the other hand, if the container uses storage exported from the underlying host, then it may be more appropriate to use the promotion score on the underlying host. Since this depends on the particular situation, the ``container-attribute-target`` resource meta-attribute allows the user to specify which approach to use. If it is set to ``host``, then user-defined node attributes will be checked on the underlying host. If it is anything else, the local node (in this case the bundle node) is used as usual. This only applies to user-defined attributes; the cluster will always check the local node for cluster-defined attributes such as ``#uname``. If ``container-attribute-target`` is ``host``, the cluster will pass additional environment variables to the primitive's resource agent that allow it to set node attributes appropriately: ``CRM_meta_container_attribute_target`` (identical to the meta-attribute value) and ``CRM_meta_physical_host`` (the name of the underlying host). .. note:: When called by a resource agent, the ``attrd_updater`` and ``crm_attribute`` commands will automatically check those environment variables and set attributes appropriately. .. index:: single: bundle; meta-attributes Bundle Meta-Attributes ______________________ Any meta-attribute set on a bundle will be inherited by the bundle's primitive and any resources implicitly created by Pacemaker for the bundle. This includes options such as ``priority``, ``target-role``, and ``is-managed``. See :ref:`resource_options` for more information. Bundles support clone meta-attributes including ``notify``, ``ordered``, and ``interleave``. Limitations of Bundles ______________________ Restarting pacemaker while a bundle is unmanaged or the cluster is in maintenance mode may cause the bundle to fail. Bundles may not be explicitly cloned or included in groups. This includes the bundle's primitive and any resources implicitly created by Pacemaker for the bundle. (If ``replicas`` is greater than 1, the bundle will behave like a clone implicitly.) Bundles do not have instance attributes, utilization attributes, or operations, though a bundle's primitive may have them. A bundle with a primitive can run on a Pacemaker Remote node only if the bundle uses a distinct ``control-port``. .. [#] Of course, the service must support running multiple instances. .. [#] Docker is a trademark of Docker, Inc. No endorsement by or association with Docker, Inc. is implied. diff --git a/doc/sphinx/Pacemaker_Explained/constraints.rst b/doc/sphinx/Pacemaker_Explained/constraints.rst index 7d2f39c58e..10f7b1dd91 100644 --- a/doc/sphinx/Pacemaker_Explained/constraints.rst +++ b/doc/sphinx/Pacemaker_Explained/constraints.rst @@ -1,1142 +1,1142 @@ .. index:: single: constraint single: resource; constraint .. _constraints: Resource Constraints -------------------- .. _location-constraint: .. index:: single: location constraint single: constraint; location Deciding Which Nodes a Resource Can Run On ########################################## *Location constraints* tell the cluster which nodes a resource can run on. There are two alternative strategies. One way is to say that, by default, resources can run anywhere, and then the location constraints specify nodes that are not allowed (an *opt-out* cluster). The other way is to start with nothing able to run anywhere, and use location constraints to selectively enable allowed nodes (an *opt-in* cluster). Whether you should choose opt-in or opt-out depends on your personal preference and the make-up of your cluster. If most of your resources can run on most of the nodes, then an opt-out arrangement is likely to result in a simpler configuration. On the other-hand, if most resources can only run on a small subset of nodes, an opt-in configuration might be simpler. .. index:: pair: XML element; rsc_location single: constraint; rsc_location Location Properties ___________________ .. list-table:: **Attributes of a rsc_location Element** :class: longtable - :widths: 1 1 1 4 + :widths: 15 15 10 60 :header-rows: 1 * - Name - Type - Default - Description * - .. rsc_location_id: .. index:: single: rsc_location; attribute, id single: attribute; id (rsc_location) single: id; rsc_location attribute id - :ref:`id ` - - A unique name for the constraint (required) * - .. rsc_location_rsc: .. index:: single: rsc_location; attribute, rsc single: attribute; rsc (rsc_location) single: rsc; rsc_location attribute rsc - :ref:`id ` - - The name of the resource to which this constraint applies. A location constraint must either have a ``rsc``, have a ``rsc-pattern``, or contain at least one resource set. * - .. rsc_pattern: .. index:: single: rsc_location; attribute, rsc-pattern single: attribute; rsc-pattern (rsc_location) single: rsc-pattern; rsc_location attribute rsc-pattern - :ref:`text ` - - A pattern matching the names of resources to which this constraint applies. The syntax is the same as `POSIX `_ extended regular expressions, with the addition of an initial ``!`` indicating that resources *not* matching the pattern are selected. If the regular expression contains submatches, and the constraint contains a :ref:`rule `, the submatches can be referenced as ``%1`` through ``%9`` in the rule's ``score-attribute`` or a rule expression's ``attribute`` (see :ref:`s-rsc-pattern-rules`). A location constraint must either have a ``rsc``, have a ``rsc-pattern``, or contain at least one resource set. * - .. rsc_location_node: .. index:: single: rsc_location; attribute, node single: attribute; node (rsc_location) single: node; rsc_location attribute node - :ref:`text ` - - The name of the node to which this constraint applies. A location constraint must either have a ``node`` and ``score``, or contain at least one rule. * - .. rsc_location_score: .. index:: single: rsc_location; attribute, score single: attribute; score (rsc_location) single: score; rsc_location attribute score - :ref:`score ` - - Positive values indicate a preference for running the affected resource(s) on ``node`` -- the higher the value, the stronger the preference. Negative values indicate the resource(s) should avoid this node (a value of **-INFINITY** changes "should" to "must"). A location constraint must either have a ``node`` and ``score``, or contain at least one rule. * - .. rsc_location_role: .. index:: single: rsc_location; attribute, role single: attribute; role (rsc_location) single: role; rsc_location attribute role - :ref:`enumeration ` - ``Started`` - This is significant only for :ref:`promotable clones `, is allowed only if ``rsc`` or ``rsc-pattern`` is set, and is ignored if the constraint contains a rule. Allowed values: * ``Started`` or ``Unpromoted``: The constraint affects the location of all instances of the resource. (A promoted instance must start in the unpromoted role before being promoted, so any location requirement for unpromoted instances also affects promoted instances.) * ``Promoted``: The constraint does not affect the location of instances, but instead affects which of the instances will be promoted. * - .. resource_discovery: .. index:: single: rsc_location; attribute, resource-discovery single: attribute; resource-discovery (rsc_location) single: resource-discovery; rsc_location attribute resource-discovery - :ref:`enumeration ` - always - Whether Pacemaker should perform resource discovery (that is, check whether the resource is already running) for this resource on this node. This should normally be left as the default, so that rogue instances of a service can be stopped when they are running where they are not supposed to be. However, there are two situations where disabling resource discovery is a good idea: when a service is not installed on a node, discovery might return an error (properly written OCF agents will not, so this is usually only seen with other agent types); and when Pacemaker Remote is used to scale a cluster to hundreds of nodes, limiting resource discovery to allowed nodes can significantly boost performance. Allowed values: * ``always:`` Always perform resource discovery for the specified resource on this node. * ``never:`` Never perform resource discovery for the specified resource on this node. This option should generally be used with a -INFINITY score, although that is not strictly required. * ``exclusive:`` Perform resource discovery for the specified resource only on this node (and other nodes similarly marked as ``exclusive``). Multiple location constraints using ``exclusive`` discovery for the same resource across different nodes creates a subset of nodes resource-discovery is exclusive to. If a resource is marked for ``exclusive`` discovery on one or more nodes, that resource is only allowed to be placed within that subset of nodes. .. warning:: Setting ``resource-discovery`` to ``never`` or ``exclusive`` removes Pacemaker's ability to detect and stop unwanted instances of a service running where it's not supposed to be. It is up to the system administrator (you!) to make sure that the service can *never* be active on nodes without ``resource-discovery`` (such as by leaving the relevant software uninstalled). .. index:: single: Asymmetrical Clusters single: Opt-In Clusters Asymmetrical "Opt-In" Clusters ______________________________ To create an opt-in cluster, start by preventing resources from running anywhere by default: .. code-block:: none # crm_attribute --name symmetric-cluster --update false Then start enabling nodes. The following fragment says that the web server prefers **sles-1**, the database prefers **sles-2** and both can fail over to **sles-3** if their most preferred node fails. .. topic:: Opt-in location constraints for two resources .. code-block:: xml .. index:: single: Symmetrical Clusters single: Opt-Out Clusters Symmetrical "Opt-Out" Clusters ______________________________ To create an opt-out cluster, start by allowing resources to run anywhere by default: .. code-block:: none # crm_attribute --name symmetric-cluster --update true Then start disabling nodes. The following fragment is the equivalent of the above opt-in configuration. .. topic:: Opt-out location constraints for two resources .. code-block:: xml .. _node-score-equal: What if Two Nodes Have the Same Score _____________________________________ If two nodes have the same score, then the cluster will choose one. This choice may seem random and may not be what was intended, however the cluster was not given enough information to know any better. .. topic:: Constraints where a resource prefers two nodes equally .. code-block:: xml In the example above, assuming no other constraints and an inactive cluster, **Webserver** would probably be placed on **sles-1** and **Database** on **sles-2**. It would likely have placed **Webserver** based on the node's uname and **Database** based on the desire to spread the resource load evenly across the cluster. However other factors can also be involved in more complex configurations. .. _s-rsc-pattern: Specifying locations using pattern matching ___________________________________________ A location constraint can affect all resources whose IDs match a given pattern. The following example bans resources named **ip-httpd**, **ip-asterisk**, **ip-gateway**, etc., from **node1**. .. topic:: Location constraint banning all resources matching a pattern from one node .. code-block:: xml .. index:: single: constraint; ordering single: resource; start order .. _s-resource-ordering: Specifying the Order in which Resources Should Start/Stop ######################################################### *Ordering constraints* tell the cluster the order in which certain resource actions should occur. .. important:: Ordering constraints affect *only* the ordering of resource actions; they do *not* require that the resources be placed on the same node. If you want resources to be started on the same node *and* in a specific order, you need both an ordering constraint *and* a colocation constraint (see :ref:`s-resource-colocation`), or alternatively, a group (see :ref:`group-resources`). .. index:: pair: XML element; rsc_order pair: constraint; rsc_order Ordering Properties ___________________ .. table:: **Attributes of a rsc_order Element** :class: longtable - :widths: 1 2 4 + :widths: 15 30 55 +--------------+----------------------------+-------------------------------------------------------------------+ | Field | Default | Description | +==============+============================+===================================================================+ | id | | .. index:: | | | | single: rsc_order; attribute, id | | | | single: attribute; id (rsc_order) | | | | single: id; rsc_order attribute | | | | | | | | A unique name for the constraint | +--------------+----------------------------+-------------------------------------------------------------------+ | first | | .. index:: | | | | single: rsc_order; attribute, first | | | | single: attribute; first (rsc_order) | | | | single: first; rsc_order attribute | | | | | | | | Name of the resource that the ``then`` resource | | | | depends on | +--------------+----------------------------+-------------------------------------------------------------------+ | then | | .. index:: | | | | single: rsc_order; attribute, then | | | | single: attribute; then (rsc_order) | | | | single: then; rsc_order attribute | | | | | | | | Name of the dependent resource | +--------------+----------------------------+-------------------------------------------------------------------+ | first-action | start | .. index:: | | | | single: rsc_order; attribute, first-action | | | | single: attribute; first-action (rsc_order) | | | | single: first-action; rsc_order attribute | | | | | | | | The action that the ``first`` resource must complete | | | | before ``then-action`` can be initiated for the ``then`` | | | | resource. Allowed values: ``start``, ``stop``, | | | | ``promote``, ``demote``. | +--------------+----------------------------+-------------------------------------------------------------------+ | then-action | value of ``first-action`` | .. index:: | | | | single: rsc_order; attribute, then-action | | | | single: attribute; then-action (rsc_order) | | | | single: first-action; rsc_order attribute | | | | | | | | The action that the ``then`` resource can execute only | | | | after the ``first-action`` on the ``first`` resource has | | | | completed. Allowed values: ``start``, ``stop``, | | | | ``promote``, ``demote``. | +--------------+----------------------------+-------------------------------------------------------------------+ | kind | Mandatory | .. index:: | | | | single: rsc_order; attribute, kind | | | | single: attribute; kind (rsc_order) | | | | single: kind; rsc_order attribute | | | | | | | | How to enforce the constraint. Allowed values: | | | | | | | | * ``Mandatory:`` ``then-action`` will never be initiated | | | | for the ``then`` resource unless and until ``first-action`` | | | | successfully completes for the ``first`` resource. | | | | | | | | * ``Optional:`` The constraint applies only if both specified | | | | resource actions are scheduled in the same transition | | | | (that is, in response to the same cluster state). This | | | | means that ``then-action`` is allowed on the ``then`` | | | | resource regardless of the state of the ``first`` resource, | | | | but if both actions happen to be scheduled at the same time, | | | | they will be ordered. | | | | | | | | * ``Serialize:`` Ensure that the specified actions are never | | | | performed concurrently for the specified resources. | | | | ``First-action`` and ``then-action`` can be executed in either | | | | order, but one must complete before the other can be initiated. | | | | An example use case is when resource start-up puts a high load | | | | on the host. | +--------------+----------------------------+-------------------------------------------------------------------+ | symmetrical | TRUE for ``Mandatory`` and | .. index:: | | | ``Optional`` kinds. FALSE | single: rsc_order; attribute, symmetrical | | | for ``Serialize`` kind. | single: attribute; symmetrical (rsc)order) | | | | single: symmetrical; rsc_order attribute | | | | | | | | If true, the reverse of the constraint applies for the | | | | opposite action (for example, if B starts after A starts, | | | | then B stops before A stops). ``Serialize`` orders cannot | | | | be symmetrical. | +--------------+----------------------------+-------------------------------------------------------------------+ ``Promote`` and ``demote`` apply to :ref:`promotable ` clone resources. Optional and mandatory ordering _______________________________ Here is an example of ordering constraints where **Database** *must* start before **Webserver**, and **IP** *should* start before **Webserver** if they both need to be started: .. topic:: Optional and mandatory ordering constraints .. code-block:: xml Because the above example lets ``symmetrical`` default to TRUE, **Webserver** must be stopped before **Database** can be stopped, and **Webserver** should be stopped before **IP** if they both need to be stopped. Symmetric and asymmetric ordering _________________________________ A mandatory symmetric ordering of "start A then start B" implies not only that the start actions must be ordered, but that B is not allowed to be active unless A is active. For example, if the ordering is added to the configuration when A is stopped (due to target-role, failure, etc.) and B is already active, then B will be stopped. By contrast, asymmetric ordering of "start A then start B" means the stops can occur in either order, which implies that B *can* remain active in the same situation. .. index:: single: colocation single: constraint; colocation single: resource; location relative to other resources .. _s-resource-colocation: Placing Resources Relative to other Resources ############################################# *Colocation constraints* tell the cluster that the location of one resource depends on the location of another one. Colocation has an important side-effect: it affects the order in which resources are assigned to a node. Think about it: You can't place A relative to B unless you know where B is [#]_. So when you are creating colocation constraints, it is important to consider whether you should colocate A with B, or B with A. .. important:: Colocation constraints affect *only* the placement of resources; they do *not* require that the resources be started in a particular order. If you want resources to be started on the same node *and* in a specific order, you need both an ordering constraint (see :ref:`s-resource-ordering`) *and* a colocation constraint, or alternatively, a group (see :ref:`group-resources`). .. index:: pair: XML element; rsc_colocation single: constraint; rsc_colocation Colocation Properties _____________________ .. table:: **Attributes of a rsc_colocation Constraint** :class: longtable - :widths: 2 2 5 + :widths: 15 30 55 +----------------+----------------+--------------------------------------------------------+ | Field | Default | Description | +================+================+========================================================+ | id | | .. index:: | | | | single: rsc_colocation; attribute, id | | | | single: attribute; id (rsc_colocation) | | | | single: id; rsc_colocation attribute | | | | | | | | A unique name for the constraint (required). | +----------------+----------------+--------------------------------------------------------+ | rsc | | .. index:: | | | | single: rsc_colocation; attribute, rsc | | | | single: attribute; rsc (rsc_colocation) | | | | single: rsc; rsc_colocation attribute | | | | | | | | The name of a resource that should be located | | | | relative to ``with-rsc``. A colocation constraint must | | | | either contain at least one | | | | :ref:`resource set `, or specify both | | | | ``rsc`` and ``with-rsc``. | +----------------+----------------+--------------------------------------------------------+ | with-rsc | | .. index:: | | | | single: rsc_colocation; attribute, with-rsc | | | | single: attribute; with-rsc (rsc_colocation) | | | | single: with-rsc; rsc_colocation attribute | | | | | | | | The name of the resource used as the colocation | | | | target. The cluster will decide where to put this | | | | resource first and then decide where to put ``rsc``. | | | | A colocation constraint must either contain at least | | | | one :ref:`resource set `, or specify | | | | both ``rsc`` and ``with-rsc``. | +----------------+----------------+--------------------------------------------------------+ | node-attribute | #uname | .. index:: | | | | single: rsc_colocation; attribute, node-attribute | | | | single: attribute; node-attribute (rsc_colocation) | | | | single: node-attribute; rsc_colocation attribute | | | | | | | | If ``rsc`` and ``with-rsc`` are specified, this node | | | | attribute must be the same on the node running ``rsc`` | | | | and the node running ``with-rsc`` for the constraint | | | | to be satisfied. (For details, see | | | | :ref:`s-coloc-attribute`.) | +----------------+----------------+--------------------------------------------------------+ | score | 0 | .. index:: | | | | single: rsc_colocation; attribute, score | | | | single: attribute; score (rsc_colocation) | | | | single: score; rsc_colocation attribute | | | | | | | | Positive values indicate the resources should run on | | | | the same node. Negative values indicate the resources | | | | should run on different nodes. Values of | | | | +/- ``INFINITY`` change "should" to "must". | +----------------+----------------+--------------------------------------------------------+ | rsc-role | Started | .. index:: | | | | single: clone; ordering constraint, rsc-role | | | | single: ordering constraint; rsc-role (clone) | | | | single: rsc-role; clone ordering constraint | | | | | | | | If ``rsc`` and ``with-rsc`` are specified, and ``rsc`` | | | | is a :ref:`promotable clone `, | | | | the constraint applies only to ``rsc`` instances in | | | | this role. Allowed values: ``Started``, ``Stopped``, | | | | ``Promoted``, ``Unpromoted``. For details, see | | | | :ref:`promotable-clone-constraints`. | +----------------+----------------+--------------------------------------------------------+ | with-rsc-role | Started | .. index:: | | | | single: clone; ordering constraint, with-rsc-role | | | | single: ordering constraint; with-rsc-role (clone) | | | | single: with-rsc-role; clone ordering constraint | | | | | | | | If ``rsc`` and ``with-rsc`` are specified, and | | | | ``with-rsc`` is a | | | | :ref:`promotable clone `, the | | | | constraint applies only to ``with-rsc`` instances in | | | | this role. Allowed values: ``Started``, ``Stopped``, | | | | ``Promoted``, ``Unpromoted``. For details, see | | | | :ref:`promotable-clone-constraints`. | +----------------+----------------+--------------------------------------------------------+ | influence | value of | .. index:: | | | ``critical`` | single: rsc_colocation; attribute, influence | | | meta-attribute | single: attribute; influence (rsc_colocation) | | | for ``rsc`` | single: influence; rsc_colocation attribute | | | | | | | | Whether to consider the location preferences of | | | | ``rsc`` when ``with-rsc`` is already active. Allowed | | | | values: ``true``, ``false``. For details, see | | | | :ref:`s-coloc-influence`. *(since 2.1.0)* | +----------------+----------------+--------------------------------------------------------+ Mandatory Placement ___________________ Mandatory placement occurs when the constraint's score is **+INFINITY** or **-INFINITY**. In such cases, if the constraint can't be satisfied, then the **rsc** resource is not permitted to run. For ``score=INFINITY``, this includes cases where the ``with-rsc`` resource is not active. If you need resource **A** to always run on the same machine as resource **B**, you would add the following constraint: .. topic:: Mandatory colocation constraint for two resources .. code-block:: xml Remember, because **INFINITY** was used, if **B** can't run on any of the cluster nodes (for whatever reason) then **A** will not be allowed to run. Whether **A** is running or not has no effect on **B**. Alternatively, you may want the opposite -- that **A** *cannot* run on the same machine as **B**. In this case, use ``score="-INFINITY"``. .. topic:: Mandatory anti-colocation constraint for two resources .. code-block:: xml Again, by specifying **-INFINITY**, the constraint is binding. So if the only place left to run is where **B** already is, then **A** may not run anywhere. As with **INFINITY**, **B** can run even if **A** is stopped. However, in this case **A** also can run if **B** is stopped, because it still meets the constraint of **A** and **B** not running on the same node. Advisory Placement __________________ If mandatory placement is about "must" and "must not", then advisory placement is the "I'd prefer if" alternative. For colocation constraints with scores greater than **-INFINITY** and less than **INFINITY**, the cluster will try to accommodate your wishes, but may ignore them if other factors outweigh the colocation score. Those factors might include other constraints, resource stickiness, failure thresholds, whether other resources would be prevented from being active, etc. .. topic:: Advisory colocation constraint for two resources .. code-block:: xml .. _s-coloc-attribute: Colocation by Node Attribute ____________________________ The ``node-attribute`` property of a colocation constraints allows you to express the requirement, "these resources must be on similar nodes". As an example, imagine that you have two Storage Area Networks (SANs) that are not controlled by the cluster, and each node is connected to one or the other. You may have two resources **r1** and **r2** such that **r2** needs to use the same SAN as **r1**, but doesn't necessarily have to be on the same exact node. In such a case, you could define a :ref:`node attribute ` named **san**, with the value **san1** or **san2** on each node as appropriate. Then, you could colocate **r2** with **r1** using ``node-attribute`` set to **san**. .. _s-coloc-influence: Colocation Influence ____________________ By default, if A is colocated with B, the cluster will take into account A's preferences when deciding where to place B, to maximize the chance that both resources can run. For a detailed look at exactly how this occurs, see `Colocation Explained `_. However, if ``influence`` is set to ``false`` in the colocation constraint, this will happen only if B is inactive and needing to be started. If B is already active, A's preferences will have no effect on placing B. An example of what effect this would have and when it would be desirable would be a nonessential reporting tool colocated with a resource-intensive service that takes a long time to start. If the reporting tool fails enough times to reach its migration threshold, by default the cluster will want to move both resources to another node if possible. Setting ``influence`` to ``false`` on the colocation constraint would mean that the reporting tool would be stopped in this situation instead, to avoid forcing the service to move. The ``critical`` resource meta-attribute is a convenient way to specify the default for all colocation constraints and groups involving a particular resource. .. note:: If a noncritical resource is a member of a group, all later members of the group will be treated as noncritical, even if they are marked as (or left to default to) critical. .. _s-resource-sets: Resource Sets ############# .. index:: single: constraint; resource set single: resource; resource set *Resource sets* allow multiple resources to be affected by a single constraint. .. topic:: A set of 3 resources .. code-block:: xml Resource sets are valid inside ``rsc_location``, ``rsc_order`` (see :ref:`s-resource-sets-ordering`), ``rsc_colocation`` (see :ref:`s-resource-sets-colocation`), and ``rsc_ticket`` (see :ref:`ticket-constraints`) constraints. A resource set has a number of properties that can be set, though not all have an effect in all contexts. .. index:: pair: XML element; resource_set .. table:: **Attributes of a resource_set Element** :class: longtable - :widths: 2 2 5 + :widths: 15 15 70 +-------------+------------------+--------------------------------------------------------+ | Field | Default | Description | +=============+==================+========================================================+ | id | | .. index:: | | | | single: resource_set; attribute, id | | | | single: attribute; id (resource_set) | | | | single: id; resource_set attribute | | | | | | | | A unique name for the set (required) | +-------------+------------------+--------------------------------------------------------+ | sequential | true | .. index:: | | | | single: resource_set; attribute, sequential | | | | single: attribute; sequential (resource_set) | | | | single: sequential; resource_set attribute | | | | | | | | Whether the members of the set must be acted on in | | | | order. Meaningful within ``rsc_order`` and | | | | ``rsc_colocation``. | +-------------+------------------+--------------------------------------------------------+ | require-all | true | .. index:: | | | | single: resource_set; attribute, require-all | | | | single: attribute; require-all (resource_set) | | | | single: require-all; resource_set attribute | | | | | | | | Whether all members of the set must be active before | | | | continuing. With the current implementation, the | | | | cluster may continue even if only one member of the | | | | set is started, but if more than one member of the set | | | | is starting at the same time, the cluster will still | | | | wait until all of those have started before continuing | | | | (this may change in future versions). Meaningful | | | | within ``rsc_order``. | +-------------+------------------+--------------------------------------------------------+ | role | | .. index:: | | | | single: resource_set; attribute, role | | | | single: attribute; role (resource_set) | | | | single: role; resource_set attribute | | | | | | | | The constraint applies only to resource set members | | | | that are :ref:`s-resource-promotable` in this | | | | role. Meaningful within ``rsc_location``, | | | | ``rsc_colocation`` and ``rsc_ticket``. | | | | Allowed values: ``Started``, ``Promoted``, | | | | ``Unpromoted``. For details, see | | | | :ref:`promotable-clone-constraints`. | +-------------+------------------+--------------------------------------------------------+ | action | start | .. index:: | | | | single: resource_set; attribute, action | | | | single: attribute; action (resource_set) | | | | single: action; resource_set attribute | | | | | | | | The action that applies to *all members* of the set. | | | | Meaningful within ``rsc_order``. Allowed values: | | | | ``start``, ``stop``, ``promote``, ``demote``. | +-------------+------------------+--------------------------------------------------------+ | score | | .. index:: | | | | single: resource_set; attribute, score | | | | single: attribute; score (resource_set) | | | | single: score; resource_set attribute | | | | | | | | *Advanced use only.* Use a specific score for this | | | | set. Meaningful within ``rsc_location`` or | | | | ``rsc_colocation``. | +-------------+------------------+--------------------------------------------------------+ | kind | | .. index:: | | | | single: resource_set; attribute, kind | | | | single: attribute; kind (resource_set) | | | | single: kind; resource_set attribute | | | | | | | | *Advanced use only.* Use a specific kind for this | | | | set. Meaningful within ``rsc_order``. | +-------------+------------------+--------------------------------------------------------+ Anti-colocation Chains ______________________ Sometimes, you would like a set of resources to be anti-colocated with each other. For example, ``resource1``, ``resource2``, and ``resource3`` must all run on different nodes. A straightforward approach would be to configure either separate colocations or a resource set, with ``-INFINITY`` scores between all the resources. However, this will not work as expected. Resource sets may in the future gain new syntax for this specific situation, but for now, a workaround is to use :ref:`utilization ` instead of colocations to keep the resources apart. Create a utilization attribute for the anti-colocation, assign the same value to each resource, and give each node the capacity to run one resource. .. _s-resource-sets-ordering: Ordering Sets of Resources ########################## A common situation is for an administrator to create a chain of ordered resources, such as: .. topic:: A chain of ordered resources .. code-block:: xml .. topic:: Visual representation of the four resources' start order for the above constraints .. image:: images/resource-set.png :alt: Ordered set Ordered Set ___________ To simplify this situation, :ref:`s-resource-sets` can be used within ordering constraints: .. topic:: A chain of ordered resources expressed as a set .. code-block:: xml While the set-based format is not less verbose, it is significantly easier to get right and maintain. .. important:: If you use a higher-level tool, pay attention to how it exposes this functionality. Depending on the tool, creating a set **A B** may be equivalent to **A then B**, or **B then A**. Ordering Multiple Sets ______________________ The syntax can be expanded to allow sets of resources to be ordered relative to each other, where the members of each individual set may be ordered or unordered (controlled by the ``sequential`` property). In the example below, **A** and **B** can both start in parallel, as can **C** and **D**, however **C** and **D** can only start once *both* **A** *and* **B** are active. .. topic:: Ordered sets of unordered resources .. code-block:: xml .. topic:: Visual representation of the start order for two ordered sets of unordered resources .. image:: images/two-sets.png :alt: Two ordered sets Of course either set -- or both sets -- of resources can also be internally ordered (by setting ``sequential="true"``) and there is no limit to the number of sets that can be specified. .. topic:: Advanced use of set ordering - Three ordered sets, two of which are internally unordered .. code-block:: xml .. topic:: Visual representation of the start order for the three sets defined above .. image:: images/three-sets.png :alt: Three ordered sets .. important:: An ordered set with ``sequential=false`` makes sense only if there is another set in the constraint. Otherwise, the constraint has no effect. Resource Set OR Logic _____________________ The unordered set logic discussed so far has all been "AND" logic. To illustrate this take the 3 resource set figure in the previous section. Those sets can be expressed, **(A and B) then (C) then (D) then (E and F)**. Say for example we want to change the first set, **(A and B)**, to use "OR" logic so the sets look like this: **(A or B) then (C) then (D) then (E and F)**. This functionality can be achieved through the use of the ``require-all`` option. This option defaults to TRUE which is why the "AND" logic is used by default. Setting ``require-all=false`` means only one resource in the set needs to be started before continuing on to the next set. .. topic:: Resource Set "OR" logic: Three ordered sets, where the first set is internally unordered with "OR" logic .. code-block:: xml .. important:: An ordered set with ``require-all=false`` makes sense only in conjunction with ``sequential=false``. Think of it like this: ``sequential=false`` modifies the set to be an unordered set using "AND" logic by default, and adding ``require-all=false`` flips the unordered set's "AND" logic to "OR" logic. .. _s-resource-sets-colocation: Colocating Sets of Resources ############################ Another common situation is for an administrator to create a set of colocated resources. The simplest way to do this is to define a resource group (see :ref:`group-resources`), but that cannot always accurately express the desired relationships. For example, maybe the resources do not need to be ordered. Another way would be to define each relationship as an individual constraint, but that causes a difficult-to-follow constraint explosion as the number of resources and combinations grow. .. topic:: Colocation chain as individual constraints, where A is placed first, then B, then C, then D .. code-block:: xml To express complicated relationships with a simplified syntax [#]_, :ref:`resource sets ` can be used within colocation constraints. .. topic:: Equivalent colocation chain expressed using **resource_set** .. code-block:: xml .. note:: Within a ``resource_set``, the resources are listed in the order they are *placed*, which is the reverse of the order in which they are *colocated*. In the above example, resource **A** is placed before resource **B**, which is the same as saying resource **B** is colocated with resource **A**. As with individual constraints, a resource that can't be active prevents any resource that must be colocated with it from being active. In both of the two previous examples, if **B** is unable to run, then both **C** and by inference **D** must remain stopped. .. important:: If you use a higher-level tool, pay attention to how it exposes this functionality. Depending on the tool, creating a set **A B** may be equivalent to **A with B**, or **B with A**. Resource sets can also be used to tell the cluster that entire *sets* of resources must be colocated relative to each other, while the individual members within any one set may or may not be colocated relative to each other (determined by the set's ``sequential`` property). In the following example, resources **B**, **C**, and **D** will each be colocated with **A** (which will be placed first). **A** must be able to run in order for any of the resources to run, but any of **B**, **C**, or **D** may be stopped without affecting any of the others. .. topic:: Using colocated sets to specify a shared dependency .. code-block:: xml .. note:: Pay close attention to the order in which resources and sets are listed. While the members of any one sequential set are placed first to last (i.e., the colocation dependency is last with first), multiple sets are placed last to first (i.e. the colocation dependency is first with last). .. important:: A colocated set with ``sequential="false"`` makes sense only if there is another set in the constraint. Otherwise, the constraint has no effect. There is no inherent limit to the number and size of the sets used. The only thing that matters is that in order for any member of one set in the constraint to be active, all members of sets listed after it must also be active (and naturally on the same node); and if a set has ``sequential="true"``, then in order for one member of that set to be active, all members listed before it must also be active. If desired, you can restrict the dependency to instances of promotable clone resources that are in a specific role, using the set's ``role`` property. .. topic:: Colocation in which the members of the middle set have no interdependencies, and the last set listed applies only to promoted instances .. code-block:: xml .. topic:: Visual representation of the above example (resources are placed from left to right) .. image:: ../shared/images/pcmk-colocated-sets.png :alt: Colocation chain .. note:: Unlike ordered sets, colocated sets do not use the ``require-all`` option. External Resource Dependencies ############################## Sometimes, a resource will depend on services that are not managed by the cluster. An example might be a resource that requires a file system that is not managed by the cluster but mounted by systemd at boot time. To accommodate this, the pacemaker systemd service depends on a normally empty target called ``resource-agents-deps.target``. The system administrator may create a unit drop-in for that target specifying the dependencies, to ensure that the services are started before Pacemaker starts and stopped after Pacemaker stops. Typically, this is accomplished by placing a unit file in the ``/etc/systemd/system/resource-agents-deps.target.d`` directory, with directives such as ``Requires`` and ``After`` specifying the dependencies as needed. .. [#] While the human brain is sophisticated enough to read the constraint in any order and choose the correct one depending on the situation, the cluster is not quite so smart. Yet. .. [#] which is not the same as saying easy to follow diff --git a/doc/sphinx/Pacemaker_Explained/fencing.rst b/doc/sphinx/Pacemaker_Explained/fencing.rst index dce479e3c6..620bba8c03 100644 --- a/doc/sphinx/Pacemaker_Explained/fencing.rst +++ b/doc/sphinx/Pacemaker_Explained/fencing.rst @@ -1,1281 +1,1281 @@ .. index:: single: fencing single: STONITH .. _fencing: Fencing ------- What Is Fencing? ################ *Fencing* is the ability to make a node unable to run resources, even when that node is unresponsive to cluster commands. Fencing is also known as *STONITH*, an acronym for "Shoot The Other Node In The Head", since the most common fencing method is cutting power to the node. Another method is "fabric fencing", cutting the node's access to some capability required to run resources (such as network access or a shared disk). .. index:: single: fencing; why necessary Why Is Fencing Necessary? ######################### Fencing protects your data from being corrupted by malfunctioning nodes or unintentional concurrent access to shared resources. Fencing protects against the "split brain" failure scenario, where cluster nodes have lost the ability to reliably communicate with each other but are still able to run resources. If the cluster just assumed that uncommunicative nodes were down, then multiple instances of a resource could be started on different nodes. The effect of split brain depends on the resource type. For example, an IP address brought up on two hosts on a network will cause packets to randomly be sent to one or the other host, rendering the IP useless. For a database or clustered file system, the effect could be much more severe, causing data corruption or divergence. Fencing is also used when a resource cannot otherwise be stopped. If a resource fails to stop on a node, it cannot be started on a different node without risking the same type of conflict as split-brain. Fencing the original node ensures the resource can be safely started elsewhere. Users may also configure the ``on-fail`` property of :ref:`operation` or the ``loss-policy`` property of :ref:`ticket constraints ` to ``fence``, in which case the cluster will fence the resource's node if the operation fails or the ticket is lost. .. index:: single: fencing; device Fence Devices ############# A *fence device* or *fencing device* is a special type of resource that provides the means to fence a node. Examples of fencing devices include intelligent power switches and IPMI devices that accept SNMP commands to cut power to a node, and iSCSI controllers that allow SCSI reservations to be used to cut a node's access to a shared disk. Since fencing devices will be used to recover from loss of networking connectivity to other nodes, it is essential that they do not rely on the same network as the cluster itself, otherwise that network becomes a single point of failure. Since loss of a node due to power outage is indistinguishable from loss of network connectivity to that node, it is also essential that at least one fence device for a node does not share power with that node. For example, an on-board IPMI controller that shares power with its host should not be used as the sole fencing device for that host. Since fencing is used to isolate malfunctioning nodes, no fence device should rely on its target functioning properly. This includes, for example, devices that ssh into a node and issue a shutdown command (such devices might be suitable for testing, but never for production). .. index:: single: fencing; agent Fence Agents ############ A *fence agent* or *fencing agent* is a ``stonith``-class resource agent. The fence agent standard provides commands (such as ``off`` and ``reboot``) that the cluster can use to fence nodes. As with other resource agent classes, this allows a layer of abstraction so that Pacemaker doesn't need any knowledge about specific fencing technologies -- that knowledge is isolated in the agent. Pacemaker supports two fence agent standards, both inherited from no-longer-active projects: * Red Hat Cluster Suite (RHCS) style: These are typically installed in ``/usr/sbin`` with names starting with ``fence_``. * Linux-HA style: These typically have names starting with ``external/``. Pacemaker can support these agents using the **fence_legacy** RHCS-style agent as a wrapper, *if* support was enabled when Pacemaker was built, which requires the ``cluster-glue`` library. When a Fence Device Can Be Used ############################### Fencing devices do not actually "run" like most services. Typically, they just provide an interface for sending commands to an external device. Additionally, fencing may be initiated by Pacemaker, by other cluster-aware software such as DRBD or DLM, or manually by an administrator, at any point in the cluster life cycle, including before any resources have been started. To accommodate this, Pacemaker does not require the fence device resource to be "started" in order to be used. Whether a fence device is started or not determines whether a node runs any recurring monitor for the device, and gives the node a slight preference for being chosen to execute fencing using that device. By default, any node can execute any fencing device. If a fence device is disabled by setting its ``target-role`` to ``Stopped``, then no node can use that device. If a location constraint with a negative score prevents a specific node from "running" a fence device, then that node will never be chosen to execute fencing using the device. A node may fence itself, but the cluster will choose that only if no other nodes can do the fencing. A common configuration scenario is to have one fence device per target node. In such a case, users often configure anti-location constraints so that the target node does not monitor its own device. Limitations of Fencing Resources ################################ Fencing resources have certain limitations that other resource classes don't: * They may have only one set of meta-attributes and one set of instance attributes. * If :ref:`rules` are used to determine fencing resource options, these might be evaluated only when first read, meaning that later changes to the rules will have no effect. Therefore, it is better to avoid confusion and not use rules at all with fencing resources. These limitations could be revisited if there is sufficient user demand. .. index:: single: fencing; special instance attributes Special Meta-Attributes for Fencing Resources ############################################# The table below lists special resource meta-attributes that may be set for any fencing resource. .. table:: **Additional Properties of Fencing Resources** - :widths: 2 1 2 4 + :widths: 10 10 10 70 +----------------------+---------+--------------------+----------------------------------------+ | Field | Type | Default | Description | +======================+=========+====================+========================================+ | provides | string | | .. index:: | | | | | single: provides | | | | | | | | | | Any special capability provided by the | | | | | fence device. Currently, only one such | | | | | capability is meaningful: | | | | | :ref:`unfencing `. | +----------------------+---------+--------------------+----------------------------------------+ .. _fencing-attributes: Special Instance Attributes for Fencing Resources ################################################# The table below lists special instance attributes that may be set for any fencing resource (*not* meta-attributes, even though they are interpreted by Pacemaker rather than the fence agent). These are also listed in the man page for ``pacemaker-fenced``. .. list-table:: **Additional Properties of Fencing Resources** :class: longtable - :widths: 2 1 2 4 + :widths: 22 10 20 48 :header-rows: 1 * - Name - Type - Default - Description * - .. _primitive_stonith_timeout: .. index:: single: stonith-timeout (primitive instance attribute) stonith-timeout - :ref:`timeout ` - - This is not used by Pacemaker (see the ``pcmk_reboot_timeout``, ``pcmk_off_timeout``, etc., properties instead), but it may be used by Linux-HA fence agents. * - .. _pcmk_host_map: .. index:: single: pcmk_host_map pcmk_host_map - :ref:`text ` - - A mapping of node names to ports for devices that do not understand the node names. For example, ``node1:1;node2:2,3`` tells the cluster to use port 1 for ``node1`` and ports 2 and 3 for ``node2``. If ``pcmk_host_check`` is explicitly set to ``static-list``, either this or ``pcmk_host_list`` must be set. The port portion of the map may contain special characters such as spaces if preceded by a backslash *(since 2.1.2)*. * - .. _pcmk_host_list: .. index:: single: pcmk_host_list pcmk_host_list - :ref:`text ` - - Comma-separated list of nodes that can be targeted by this device (for example, ``node1,node2,node3``). If pcmk_host_check is ``static-list``, either this or ``pcmk_host_map`` must be set. * - .. _pcmk_host_check: .. index:: single: pcmk_host_check pcmk_host_check - :ref:`text ` - See :ref:`pcmk_host_check_default` - The method Pacemaker should use to determine which nodes can be targeted by this device. Allowed values: * ``static-list:`` targets are listed in the ``pcmk_host_list`` or ``pcmk_host_map`` attribute * ``dynamic-list:`` query the device via the agent's ``list`` action * ``status:`` query the device via the agent's ``status`` action * ``none:`` assume the device can fence any node * - .. _pcmk_delay_max: .. index:: single: pcmk_delay_max pcmk_delay_max - :ref:`duration ` - 0s - Enable a delay of no more than the time specified before executing fencing actions. Pacemaker derives the overall delay by taking the value of pcmk_delay_base and adding a random delay value such that the sum is kept below this maximum. This is sometimes used in two-node clusters to ensure that the nodes don't fence each other at the same time. * - .. _pcmk_delay_base: .. index:: single: pcmk_delay_base pcmk_delay_base - :ref:`text ` - 0s - Enable a static delay before executing fencing actions. This can be used, for example, in two-node clusters to ensure that the nodes don't fence each other, by having separate fencing resources with different values. The node that is fenced with the shorter delay will lose a fencing race. The overall delay introduced by pacemaker is derived from this value plus a random delay such that the sum is kept below the maximum delay. A single device can have different delays per node using a host map *(since 2.1.2)*, for example ``node1:0s;node2:5s.`` * - .. _pcmk_action_limit: .. index:: single: pcmk_action_limit pcmk_action_limit - :ref:`integer ` - 1 - The maximum number of actions that can be performed in parallel on this device. A value of -1 means unlimited. Node fencing actions initiated by the cluster (as opposed to an administrator running the ``stonith_admin`` tool or the fencer running recurring device monitors and ``status`` and ``list`` commands) are additionally subject to the ``concurrent-fencing`` cluster property. * - .. _pcmk_host_argument: .. index:: single: pcmk_host_argument pcmk_host_argument - :ref:`text ` - ``port`` if the fence agent metadata advertises support for it, otherwise ``plug`` if supported, otherwise ``none`` - *Advanced use only.* Which parameter should be supplied to the fence agent to identify the node to be fenced. A value of ``none`` tells the cluster not to supply any additional parameters. * - .. _pcmk_reboot_action: .. index:: single: pcmk_reboot_action pcmk_reboot_action - :ref:`text ` - ``reboot`` - *Advanced use only.* The command to send to the resource agent in order to reboot a node. Some devices do not support the standard commands or may provide additional ones. Use this to specify an alternate, device-specific command. * - .. _pcmk_reboot_timeout: .. index:: single: pcmk_reboot_timeout pcmk_reboot_timeout - :ref:`timeout ` - 60s - *Advanced use only.* Specify an alternate timeout (in seconds) to use for ``reboot`` actions instead of the value of ``stonith-timeout``. Some devices need much more or less time to complete than normal. Use this to specify an alternate, device-specific timeout. * - .. _pcmk_reboot_retries: .. index:: single: pcmk_reboot_retries pcmk_reboot_retries - :ref:`integer ` - 2 - *Advanced use only.* The maximum number of times to retry the ``reboot`` command within the timeout period. Some devices do not support multiple connections, and operations may fail if the device is busy with another task, so Pacemaker will automatically retry the operation, if there is time remaining. Use this option to alter the number of times Pacemaker retries before giving up. * - .. _pcmk_off_action: .. index:: single: pcmk_off_action pcmk_off_action - :ref:`text ` - ``off`` - *Advanced use only.* The command to send to the resource agent in order to shut down a node. Some devices do not support the standard commands or may provide additional ones. Use this to specify an alternate, device-specific command. * - .. _pcmk_off_timeout: .. index:: single: pcmk_off_timeout pcmk_off_timeout - :ref:`timeout ` - 60s - *Advanced use only.* Specify an alternate timeout (in seconds) to use for ``off`` actions instead of the value of ``stonith-timeout``. Some devices need much more or less time to complete than normal. Use this to specify an alternate, device-specific timeout. * - .. _pcmk_off_retries: .. index:: single: pcmk_off_retries pcmk_off_retries - :ref:`integer ` - 2 - *Advanced use only.* The maximum number of times to retry the ``off`` command within the timeout period. Some devices do not support multiple connections, and operations may fail if the device is busy with another task, so Pacemaker will automatically retry the operation, if there is time remaining. Use this option to alter the number of times Pacemaker retries before giving up. * - .. _pcmk_list_action: .. index:: single: pcmk_list_action pcmk_list_action - :ref:`text ` - ``list`` - *Advanced use only.* The command to send to the resource agent in order to list nodes. Some devices do not support the standard commands or may provide additional ones. Use this to specify an alternate, device-specific command. * - .. _pcmk_list_timeout: .. index:: single: pcmk_list_timeout pcmk_list_timeout - :ref:`timeout ` - 60s - *Advanced use only.* Specify an alternate timeout (in seconds) to use for ``list`` actions instead of the value of ``stonith-timeout``. Some devices need much more or less time to complete than normal. Use this to specify an alternate, device-specific timeout. * - .. _pcmk_list_retries: .. index:: single: pcmk_list_retries pcmk_list_retries - :ref:`integer ` - 2 - *Advanced use only.* The maximum number of times to retry the ``list`` command within the timeout period. Some devices do not support multiple connections, and operations may fail if the device is busy with another task, so Pacemaker will automatically retry the operation, if there is time remaining. Use this option to alter the number of times Pacemaker retries before giving up. * - .. _pcmk_monitor_action: .. index:: single: pcmk_monitor_action pcmk_monitor_action - :ref:`text ` - ``monitor`` - *Advanced use only.* The command to send to the resource agent in order to report extended status. Some devices do not support the standard commands or may provide additional ones. Use this to specify an alternate, device-specific command. * - .. _pcmk_monitor_timeout: .. index:: single: pcmk_monitor_timeout pcmk_monitor_timeout - :ref:`timeout ` - 60s - *Advanced use only.* Specify an alternate timeout (in seconds) to use for ``monitor`` actions instead of the value of ``stonith-timeout``. Some devices need much more or less time to complete than normal. Use this to specify an alternate, device-specific timeout. * - .. _pcmk_monitor_retries: .. index:: single: pcmk_monitor_retries pcmk_monitor_retries - :ref:`integer ` - 2 - *Advanced use only.* The maximum number of times to retry the ``monitor`` command within the timeout period. Some devices do not support multiple connections, and operations may fail if the device is busy with another task, so Pacemaker will automatically retry the operation, if there is time remaining. Use this option to alter the number of times Pacemaker retries before giving up. * - .. _pcmk_status_action: .. index:: single: pcmk_status_action pcmk_status_action - :ref:`text ` - ``status`` - *Advanced use only.* The command to send to the resource agent in order to report status. Some devices do not support the standard commands or may provide additional ones. Use this to specify an alternate, device-specific command. * - .. _pcmk_status_timeout: .. index:: single: pcmk_status_timeout pcmk_status_timeout - :ref:`timeout ` - 60s - *Advanced use only.* Specify an alternate timeout (in seconds) to use for ``status`` actions instead of the value of ``stonith-timeout``. Some devices need much more or less time to complete than normal. Use this to specify an alternate, device-specific timeout. * - .. _pcmk_status_retries: .. index:: single: pcmk_status_retries pcmk_status_retries - :ref:`integer ` - 2 - *Advanced use only.* The maximum number of times to retry the ``status`` command within the timeout period. Some devices do not support multiple connections, and operations may fail if the device is busy with another task, so Pacemaker will automatically retry the operation, if there is time remaining. Use this option to alter the number of times Pacemaker retries before giving up. .. _pcmk_host_check_default: Default Check Type ################## If the user does not explicitly configure ``pcmk_host_check`` for a fence device, a default value appropriate to other configured parameters will be used: * If either ``pcmk_host_list`` or ``pcmk_host_map`` is configured, ``static-list`` will be used; * otherwise, if the fence device supports the ``list`` action, and the first attempt at using ``list`` succeeds, ``dynamic-list`` will be used; * otherwise, if the fence device supports the ``status`` action, ``status`` will be used; * otherwise, ``none`` will be used. .. index:: single: unfencing single: fencing; unfencing .. _unfencing: Unfencing ######### With fabric fencing (such as cutting network or shared disk access rather than power), it is expected that the cluster will fence the node, and then a system administrator must manually investigate what went wrong, correct any issues found, then reboot (or restart the cluster services on) the node. Once the node reboots and rejoins the cluster, some fabric fencing devices require an explicit command to restore the node's access. This capability is called *unfencing* and is typically implemented as the fence agent's ``on`` command. If any cluster resource has ``requires`` set to ``unfencing``, then that resource will not be probed or started on a node until that node has been unfenced. Fencing and Quorum ################## In general, a cluster partition may execute fencing only if the partition has quorum, and the ``stonith-enabled`` cluster property is set to true. However, there are exceptions: * The requirements apply only to fencing initiated by Pacemaker. If an administrator initiates fencing using the ``stonith_admin`` command, or an external application such as DLM initiates fencing using Pacemaker's C API, the requirements do not apply. * A cluster partition without quorum is allowed to fence any active member of that partition. As a corollary, this allows a ``no-quorum-policy`` of ``suicide`` to work. * If the ``no-quorum-policy`` cluster property is set to ``ignore``, then quorum is not required to execute fencing of any node. Fencing Timeouts ################ Fencing timeouts are complicated, since a single fencing operation can involve many steps, each of which may have a separate timeout. Fencing may be initiated in one of several ways: * An administrator may initiate fencing using the ``stonith_admin`` tool, which has a ``--timeout`` option (defaulting to 2 minutes) that will be used as the fence operation timeout. * An external application such as DLM may initiate fencing using the Pacemaker C API. The application will specify the fence operation timeout in this case, which might or might not be configurable by the user. * The cluster may initiate fencing itself. In this case, the ``stonith-timeout`` cluster property (defaulting to 1 minute) will be used as the fence operation timeout. However fencing is initiated, the initiator contacts Pacemaker's fencer (``pacemaker-fenced``) to request fencing. This connection and request has its own timeout, separate from the fencing operation timeout, but usually happens very quickly. The fencer will contact all fencers in the cluster to ask what devices they have available to fence the target node. The fence operation timeout will be used as the timeout for each of these queries. Once a fencing device has been selected, the fencer will check whether any action-specific timeout has been configured for the device, to use instead of the fence operation timeout. For example, if ``stonith-timeout`` is 60 seconds, but the fencing device has ``pcmk_reboot_timeout`` configured as 90 seconds, then a timeout of 90 seconds will be used for reboot actions using that device. A device may have retries configured, in which case the timeout applies across all attempts. For example, if a device has ``pcmk_reboot_retries`` configured as 2, and the first reboot attempt fails, the second attempt will only have whatever time is remaining in the action timeout after subtracting how much time the first attempt used. This means that if the first attempt fails due to using the entire timeout, no further attempts will be made. There is currently no way to configure a per-attempt timeout. If more than one device is required to fence a target, whether due to failure of the first device or a fencing topology with multiple devices configured for the target, each device will have its own separate action timeout. For all of the above timeouts, the fencer will generally multiply the configured value by 1.2 to get an actual value to use, to account for time needed by the fencer's own processing. Separate from the fencer's timeouts, some fence agents have internal timeouts for individual steps of their fencing process. These agents often have parameters to configure these timeouts, such as ``login-timeout``, ``shell-timeout``, or ``power-timeout``. Many such agents also have a ``disable-timeout`` parameter to ignore their internal timeouts and just let Pacemaker handle the timeout. This causes a difference in retry behavior. If ``disable-timeout`` is not set, and the agent hits one of its internal timeouts, it will report that as a failure to Pacemaker, which can then retry. If ``disable-timeout`` is set, and Pacemaker hits a timeout for the agent, then there will be no time remaining, and no retry will be done. Fence Devices Dependent on Other Resources ########################################## In some cases, a fence device may require some other cluster resource (such as an IP address) to be active in order to function properly. This is obviously undesirable in general: fencing may be required when the depended-on resource is not active, or fencing may be required because the node running the depended-on resource is no longer responding. However, this may be acceptable under certain conditions: * The dependent fence device should not be able to target any node that is allowed to run the depended-on resource. * The depended-on resource should not be disabled during production operation. * The ``concurrent-fencing`` cluster property should be set to ``true``. Otherwise, if both the node running the depended-on resource and some node targeted by the dependent fence device need to be fenced, the fencing of the node running the depended-on resource might be ordered first, making the second fencing impossible and blocking further recovery. With concurrent fencing, the dependent fence device might fail at first due to the depended-on resource being unavailable, but it will be retried and eventually succeed once the resource is brought back up. Even under those conditions, there is one unlikely problem scenario. The DC always schedules fencing of itself after any other fencing needed, to avoid unnecessary repeated DC elections. If the dependent fence device targets the DC, and both the DC and a different node running the depended-on resource need to be fenced, the DC fencing will always fail and block further recovery. Note, however, that losing a DC node entirely causes some other node to become DC and schedule the fencing, so this is only a risk when a stop or other operation with ``on-fail`` set to ``fencing`` fails on the DC. .. index:: single: fencing; configuration Configuring Fencing ################### Higher-level tools can provide simpler interfaces to this process, but using Pacemaker command-line tools, this is how you could configure a fence device. #. Find the correct driver: .. code-block:: none # stonith_admin --list-installed .. note:: You may have to install packages to make fence agents available on your host. Searching your available packages for ``fence-`` is usually helpful. Ensure the packages providing the fence agents you require are installed on every cluster node. #. Find the required parameters associated with the device (replacing ``$AGENT_NAME`` with the name obtained from the previous step): .. code-block:: none # stonith_admin --metadata --agent $AGENT_NAME #. Create a file called ``stonith.xml`` containing a primitive resource with a class of ``stonith``, a type equal to the agent name obtained earlier, and a parameter for each of the values returned in the previous step. #. If the device does not know how to fence nodes based on their uname, you may also need to set the special ``pcmk_host_map`` parameter. See :ref:`fencing-attributes` for details. #. If the device does not support the ``list`` command, you may also need to set the special ``pcmk_host_list`` and/or ``pcmk_host_check`` parameters. See :ref:`fencing-attributes` for details. #. If the device does not expect the target to be specified with the ``port`` parameter, you may also need to set the special ``pcmk_host_argument`` parameter. See :ref:`fencing-attributes` for details. #. Upload it into the CIB using cibadmin: .. code-block:: none # cibadmin --create --scope resources --xml-file stonith.xml #. Set ``stonith-enabled`` to true: .. code-block:: none # crm_attribute --type crm_config --name stonith-enabled --update true #. Once the stonith resource is running, you can test it by executing the following, replacing ``$NODE_NAME`` with the name of the node to fence (although you might want to stop the cluster on that machine first): .. code-block:: none # stonith_admin --reboot $NODE_NAME Example Fencing Configuration _____________________________ For this example, we assume we have a cluster node, ``pcmk-1``, whose IPMI controller is reachable at the IP address 192.0.2.1. The IPMI controller uses the username ``testuser`` and the password ``abc123``. #. Looking at what's installed, we may see a variety of available agents: .. code-block:: none # stonith_admin --list-installed .. code-block:: none (... some output omitted ...) fence_idrac fence_ilo3 fence_ilo4 fence_ilo5 fence_imm fence_ipmilan (... some output omitted ...) Perhaps after some reading some man pages and doing some Internet searches, we might decide ``fence_ipmilan`` is our best choice. #. Next, we would check what parameters ``fence_ipmilan`` provides: .. code-block:: none # stonith_admin --metadata -a fence_ipmilan .. code-block:: xml fence_ipmilan is an I/O Fencing agentwhich can be used with machines controlled by IPMI.This agent calls support software ipmitool (http://ipmitool.sf.net/). WARNING! This fence agent might report success before the node is powered off. You should use -m/method onoff if your fence device works correctly with that option. Fencing action IPMI Lan Auth type. Ciphersuite to use (same as ipmitool -C parameter) Hexadecimal-encoded Kg key for IPMIv2 authentication IP address or hostname of fencing device IP address or hostname of fencing device TCP/UDP port to use for connection with device Use Lanplus to improve security of connection Login name Method to fence Login password or passphrase Script to run to retrieve password Login password or passphrase Script to run to retrieve password IP address or hostname of fencing device (together with --port-as-ip) IP address or hostname of fencing device (together with --port-as-ip) Privilege level on IPMI device Bridge IPMI requests to the remote target address Login name Disable logging to stderr. Does not affect --verbose or --debug-file or logging to syslog. Verbose mode Write debug information to given file Write debug information to given file Display version information and exit Display help and exit Wait X seconds before fencing is started Path to ipmitool binary Wait X seconds for cmd prompt after login Make "port/plug" to be an alias to IP address Test X seconds for status change after ON/OFF Wait X seconds after issuing ON/OFF Wait X seconds for cmd prompt after issuing command Count of attempts to retry power on Use sudo (without password) when calling 3rd party software Use sudo (without password) when calling 3rd party software Path to sudo binary Once we've decided what parameter values we think we need, it is a good idea to run the fence agent's status action manually, to verify that our values work correctly: .. code-block:: none # fence_ipmilan --lanplus -a 192.0.2.1 -l testuser -p abc123 -o status Chassis Power is on #. Based on that, we might create a fencing resource configuration like this in ``stonith.xml`` (or any file name, just use the same name with ``cibadmin`` later): .. code-block:: xml .. note:: Even though the man page shows that the ``action`` parameter is supported, we do not provide that in the resource configuration. Pacemaker will supply an appropriate action whenever the fence device must be used. #. In this case, we don't need to configure ``pcmk_host_map`` because ``fence_ipmilan`` ignores the target node name and instead uses its ``ip`` parameter to know how to contact the IPMI controller. #. We do need to let Pacemaker know which cluster node can be fenced by this device, since ``fence_ipmilan`` doesn't support the ``list`` action. Add a line like this to the agent's instance attributes: .. code-block:: xml #. We don't need to configure ``pcmk_host_argument`` since ``ip`` is all the fence agent needs (it ignores the target name). #. Make the configuration active: .. code-block:: none # cibadmin --create --scope resources --xml-file stonith.xml #. Set ``stonith-enabled`` to true (this only has to be done once): .. code-block:: none # crm_attribute --type crm_config --name stonith-enabled --update true #. Since our cluster is still in testing, we can reboot ``pcmk-1`` without bothering anyone, so we'll test our fencing configuration by running this from one of the other cluster nodes: .. code-block:: none # stonith_admin --reboot pcmk-1 Then we will verify that the node did, in fact, reboot. We can repeat that process to create a separate fencing resource for each node. With some other fence device types, a single fencing resource is able to be used for all nodes. In fact, we could do that with ``fence_ipmilan``, using the ``port-as-ip`` parameter along with ``pcmk_host_map``. Either approach is fine. .. index:: single: fencing; topology single: fencing-topology single: fencing-level Fencing Topologies ################## Pacemaker supports fencing nodes with multiple devices through a feature called *fencing topologies*. Fencing topologies may be used to provide alternative devices in case one fails, or to require multiple devices to all be executed successfully in order to consider the node successfully fenced, or even a combination of the two. Create the individual devices as you normally would, then define one or more ``fencing-level`` entries in the ``fencing-topology`` section of the configuration. * Each fencing level is attempted in order of ascending ``index``. Allowed values are 1 through 9. * If a device fails, processing terminates for the current level. No further devices in that level are exercised, and the next level is attempted instead. * If the operation succeeds for all the listed devices in a level, the level is deemed to have passed. * The operation is finished when a level has passed (success), or all levels have been attempted (failed). * If the operation failed, the next step is determined by the scheduler and/or the controller. Some possible uses of topologies include: * Try on-board IPMI, then an intelligent power switch if that fails * Try fabric fencing of both disk and network, then fall back to power fencing if either fails * Wait up to a certain time for a kernel dump to complete, then cut power to the node .. table:: **Attributes of a fencing-level Element** :class: longtable - :widths: 1 4 + :widths: 25 75 +------------------+-----------------------------------------------------------------------------------------+ | Attribute | Description | +==================+=========================================================================================+ | id | .. index:: | | | pair: fencing-level; id | | | | | | A unique name for this element (required) | +------------------+-----------------------------------------------------------------------------------------+ | target | .. index:: | | | pair: fencing-level; target | | | | | | The name of a single node to which this level applies | +------------------+-----------------------------------------------------------------------------------------+ | target-pattern | .. index:: | | | pair: fencing-level; target-pattern | | | | | | An extended regular expression (as defined in `POSIX | | | `_) | | | matching the names of nodes to which this level applies | +------------------+-----------------------------------------------------------------------------------------+ | target-attribute | .. index:: | | | pair: fencing-level; target-attribute | | | | | | The name of a node attribute that is set (to ``target-value``) for nodes to which this | | | level applies | +------------------+-----------------------------------------------------------------------------------------+ | target-value | .. index:: | | | pair: fencing-level; target-value | | | | | | The node attribute value (of ``target-attribute``) that is set for nodes to which this | | | level applies | +------------------+-----------------------------------------------------------------------------------------+ | index | .. index:: | | | pair: fencing-level; index | | | | | | The order in which to attempt the levels. Levels are attempted in ascending order | | | *until one succeeds*. Valid values are 1 through 9. | +------------------+-----------------------------------------------------------------------------------------+ | devices | .. index:: | | | pair: fencing-level; devices | | | | | | A comma-separated list of devices that must all be tried for this level | +------------------+-----------------------------------------------------------------------------------------+ .. note:: **Fencing topology with different devices for different nodes** .. code-block:: xml ... ... Example Dual-Layer, Dual-Device Fencing Topologies __________________________________________________ The following example illustrates an advanced use of ``fencing-topology`` in a cluster with the following properties: * 2 nodes (prod-mysql1 and prod-mysql2) * the nodes have IPMI controllers reachable at 192.0.2.1 and 192.0.2.2 * the nodes each have two independent Power Supply Units (PSUs) connected to two independent Power Distribution Units (PDUs) reachable at 198.51.100.1 (port 10 and port 11) and 203.0.113.1 (port 10 and port 11) * fencing via the IPMI controller uses the ``fence_ipmilan`` agent (1 fence device per controller, with each device targeting a separate node) * fencing via the PDUs uses the ``fence_apc_snmp`` agent (1 fence device per PDU, with both devices targeting both nodes) * a random delay is used to lessen the chance of a "death match" * fencing topology is set to try IPMI fencing first then dual PDU fencing if that fails In a node failure scenario, Pacemaker will first select ``fence_ipmilan`` to try to kill the faulty node. Using the fencing topology, if that method fails, it will then move on to selecting ``fence_apc_snmp`` twice (once for the first PDU, then again for the second PDU). The fence action is considered successful only if both PDUs report the required status. If any of them fails, fencing loops back to the first fencing method, ``fence_ipmilan``, and so on, until the node is fenced or the fencing action is cancelled. .. note:: **First fencing method: single IPMI device per target** Each cluster node has it own dedicated IPMI controller that can be contacted for fencing using the following primitives: .. code-block:: xml .. note:: **Second fencing method: dual PDU devices** Each cluster node also has 2 distinct power supplies controlled by 2 distinct PDUs: * Node 1: PDU 1 port 10 and PDU 2 port 10 * Node 2: PDU 1 port 11 and PDU 2 port 11 The matching fencing agents are configured as follows: .. code-block:: xml .. note:: **Fencing topology** Now that all the fencing resources are defined, it's time to create the right topology. We want to first fence using IPMI and if that does not work, fence both PDUs to effectively and surely kill the node. .. code-block:: xml In ``fencing-topology``, the lowest ``index`` value for a target determines its first fencing method. Remapping Reboots ################# When the cluster needs to reboot a node, whether because ``stonith-action`` is ``reboot`` or because a reboot was requested externally (such as by ``stonith_admin --reboot``), it will remap that to other commands in two cases: * If the chosen fencing device does not support the ``reboot`` command, the cluster will ask it to perform ``off`` instead. * If a fencing topology level with multiple devices must be executed, the cluster will ask all the devices to perform ``off``, then ask the devices to perform ``on``. To understand the second case, consider the example of a node with redundant power supplies connected to intelligent power switches. Rebooting one switch and then the other would have no effect on the node. Turning both switches off, and then on, actually reboots the node. In such a case, the fencing operation will be treated as successful as long as the ``off`` commands succeed, because then it is safe for the cluster to recover any resources that were on the node. Timeouts and errors in the ``on`` phase will be logged but ignored. When a reboot operation is remapped, any action-specific timeout for the remapped action will be used (for example, ``pcmk_off_timeout`` will be used when executing the ``off`` command, not ``pcmk_reboot_timeout``). diff --git a/doc/sphinx/Pacemaker_Explained/local-options.rst b/doc/sphinx/Pacemaker_Explained/local-options.rst index 64e45d0a02..c8a8ea2f1a 100644 --- a/doc/sphinx/Pacemaker_Explained/local-options.rst +++ b/doc/sphinx/Pacemaker_Explained/local-options.rst @@ -1,780 +1,780 @@ Host-Local Configuration ------------------------ .. index:: pair: XML element; configuration .. note:: Directory and file paths below may differ on your system depending on your Pacemaker build settings. Check your Pacemaker configuration file to find the correct paths. Configuration Value Types ######################### Throughout this document, configuration values will be designated as having one of the following types: .. list-table:: **Configuration Value Types** :class: longtable - :widths: 1 3 + :widths: 25 75 :header-rows: 1 * - Type - Description * - .. _boolean: .. index:: pair: type; boolean boolean - Case-insensitive text value where ``1``, ``yes``, ``y``, ``on``, and ``true`` evaluate as true and ``0``, ``no``, ``n``, ``off``, ``false``, and unset evaluate as false * - .. _date_time: .. index:: pair: type; date/time date/time - Textual timestamp like ``Sat Dec 21 11:47:45 2013`` * - .. _duration: .. index:: pair: type; duration duration - A nonnegative time duration, specified either like a :ref:`timeout ` or an `ISO 8601 duration `_. A duration may be up to approximately 49 days but is intended for much smaller time periods. * - .. _enumeration: .. index:: pair: type; enumeration enumeration - Text that must be one of a set of defined values (which will be listed in the description) * - .. _epoch_time: .. index:: pair: type; epoch_time epoch_time - Time as the integer number of seconds since the Unix epoch, ``1970-01-01 00:00:00 +0000 (UTC)``. * - .. _id: .. index:: pair: type; id id - A text string starting with a letter or underbar, followed by any combination of letters, numbers, dashes, dots, and/or underbars; when used for a property named ``id``, the string must be unique across all ``id`` properties in the CIB * - .. _integer: .. index:: pair: type; integer integer - 32-bit signed integer value (-2,147,483,648 to 2,147,483,647) * - .. _iso8601: .. index:: pair: type; iso8601 ISO 8601 - An `ISO 8601 `_ date/time. * - .. _nonnegative_integer: .. index:: pair: type; nonnegative integer nonnegative integer - 32-bit nonnegative integer value (0 to 2,147,483,647) * - .. _percentage: .. index:: pair: type; percentage percentage - Floating-point number followed by an optional percent sign ('%') * - .. _port: .. index:: pair: type; port port - Integer TCP port number (0 to 65535) * - .. _range: .. index:: pair: type; range range - A range may be a single nonnegative integer or a dash-separated range of nonnegative integers. Either the first or last value may be omitted to leave the range open-ended. Examples: ``0``, ``3-``, ``-5``, ``4-6``. * - .. _score: .. index:: pair: type; score score - A Pacemaker score can be an integer between -1,000,000 and 1,000,000, or a string alias: ``INFINITY`` or ``+INFINITY`` is equivalent to 1,000,000, ``-INFINITY`` is equivalent to -1,000,000, and ``red``, ``yellow``, and ``green`` are equivalent to integers as described in :ref:`node-health`. * - .. _text: .. index:: pair: type; text text - A text string * - .. _timeout: .. index:: pair: type; timeout timeout - A time duration, specified as a bare number (in which case it is considered to be in seconds) or a number with a unit (``ms`` or ``msec`` for milliseconds, ``us`` or ``usec`` for microseconds, ``s`` or ``sec`` for seconds, ``m`` or ``min`` for minutes, ``h`` or ``hr`` for hours) optionally with whitespace before and/or after the number. * - .. _version: .. index:: pair: type; version version - Version number (any combination of alphanumeric characters, dots, and dashes, starting with a number). Scores ______ Scores are integral to how Pacemaker works. Practically everything from moving a resource to deciding which resource to stop in a degraded cluster is achieved by manipulating scores in some way. Scores are calculated per resource and node. Any node with a negative score for a resource can't run that resource. The cluster places a resource on the node with the highest score for it. Score addition and subtraction follow these rules: * Any value (including ``INFINITY``) - ``INFINITY`` = ``-INFINITY`` * ``INFINITY`` + any value other than ``-INFINITY`` = ``INFINITY`` .. note:: What if you want to use a score higher than 1,000,000? Typically this possibility arises when someone wants to base the score on some external metric that might go above 1,000,000. The short answer is you can't. The long answer is it is sometimes possible work around this limitation creatively. You may be able to set the score to some computed value based on the external metric rather than use the metric directly. For nodes, you can store the metric as a node attribute, and query the attribute when computing the score (possibly as part of a custom resource agent). Local Options ############# Most Pacemaker configuration is in the cluster-wide CIB, but some host-local configuration options either are needed at startup (before the CIB is read) or provide per-host overrides of cluster-wide options. These options are configured as environment variables set when Pacemaker is started, in the format ``=""``. These are typically set in a file whose location varies by OS (most commonly ``/etc/sysconfig/pacemaker`` or ``/etc/default/pacemaker``; this documentation was generated on a system using |PCMK_CONFIG_FILE|). .. list-table:: **Local Options** :class: longtable - :widths: 2 2 2 5 + :widths: 25 15 10 50 :header-rows: 1 * - Name - Type - Default - Description * - .. _cib_pam_service: .. index:: pair: node option; CIB_pam_service CIB_pam_service - :ref:`text ` - login - PAM service to use for remote CIB client authentication (passed to ``pam_start``). * - .. _pcmk_logfacility: .. index:: pair: node option; PCMK_logfacility PCMK_logfacility - :ref:`enumeration ` - daemon - Enable logging via the system log or journal, using the specified log facility. Messages sent here are of value to all Pacemaker administrators. This can be disabled using ``none``, but that is not recommended. Allowed values: * ``none`` * ``daemon`` * ``user`` * ``local0`` * ``local1`` * ``local2`` * ``local3`` * ``local4`` * ``local5`` * ``local6`` * ``local7`` * - .. _pcmk_logpriority: .. index:: pair: node option; PCMK_logpriority PCMK_logpriority - :ref:`enumeration ` - notice - Unless system logging is disabled using ``PCMK_logfacility=none``, messages of the specified log severity and higher will be sent to the system log. The default is appropriate for most installations. Allowed values: * ``emerg`` * ``alert`` * ``crit`` * ``error`` * ``warning`` * ``notice`` * ``info`` * ``debug`` * - .. _pcmk_logfile: .. index:: pair: node option; PCMK_logfile PCMK_logfile - :ref:`text ` - |PCMK_LOG_FILE| - Unless set to ``none``, more detailed log messages will be sent to the specified file (in addition to the system log, if enabled). These messages may have extended information, and will include messages of info severity. This log is of more use to developers and advanced system administrators, and when reporting problems. Note: The default is |PCMK_CONTAINER_LOG_FILE| (inside the container) for bundled container nodes; this would typically be mapped to a different path on the host running the container. * - .. _pcmk_logfile_mode: .. index:: pair: node option; PCMK_logfile_mode PCMK_logfile_mode - :ref:`text ` - 0660 - Pacemaker will set the permissions on the detail log to this value (see ``chmod(1)``). * - .. _pcmk_debug: .. index:: pair: node option; PCMK_debug PCMK_debug - :ref:`enumeration ` - no - Whether to send debug severity messages to the detail log. This may be set for all subsystems (``yes`` or ``no``) or for specific (comma- separated) subsystems. Allowed subsystems are: * ``pacemakerd`` * ``pacemaker-attrd`` * ``pacemaker-based`` * ``pacemaker-controld`` * ``pacemaker-execd`` * ``pacemaker-fenced`` * ``pacemaker-schedulerd`` Example: ``PCMK_debug="pacemakerd,pacemaker-execd"`` * - .. _pcmk_stderr: .. index:: pair: node option; PCMK_stderr PCMK_stderr - :ref:`boolean ` - no - *Advanced Use Only:* Whether to send daemon log messages to stderr. This would be useful only during troubleshooting, when starting Pacemaker manually on the command line. Setting this option in the configuration file is pointless, since the file is not read when starting Pacemaker manually. However, it can be set directly as an environment variable on the command line. * - .. _pcmk_trace_functions: .. index:: pair: node option; PCMK_trace_functions PCMK_trace_functions - :ref:`text ` - - *Advanced Use Only:* Send debug and trace severity messages from these (comma-separated) source code functions to the detail log. Example: ``PCMK_trace_functions="func1,func2"`` * - .. _pcmk_trace_files: .. index:: pair: node option; PCMK_trace_files PCMK_trace_files - :ref:`text ` - - *Advanced Use Only:* Send debug and trace severity messages from all functions in these (comma-separated) source file names to the detail log. Example: ``PCMK_trace_files="file1.c,file2.c"`` * - .. _pcmk_trace_formats: .. index:: pair: node option; PCMK_trace_formats PCMK_trace_formats - :ref:`text ` - - *Advanced Use Only:* Send trace severity messages that are generated by these (comma-separated) format strings in the source code to the detail log. Example: ``PCMK_trace_formats="Error: %s (%d)"`` * - .. _pcmk_trace_tags: .. index:: pair: node option; PCMK_trace_tags PCMK_trace_tags - :ref:`text ` - - *Advanced Use Only:* Send debug and trace severity messages related to these (comma-separated) resource IDs to the detail log. Example: ``PCMK_trace_tags="client-ip,dbfs"`` * - .. _pcmk_blackbox: .. index:: pair: node option; PCMK_blackbox PCMK_blackbox - :ref:`enumeration ` - no - *Advanced Use Only:* Enable blackbox logging globally (``yes`` or ``no``) or by subsystem. A blackbox contains a rolling buffer of all logs (of all severities). Blackboxes are stored under |CRM_BLACKBOX_DIR| by default, by default, and their contents can be viewed using the ``qb-blackbox(8)`` command. The blackbox recorder can be enabled at start using this variable, or at runtime by sending a Pacemaker subsystem daemon process a ``SIGUSR1`` or ``SIGTRAP`` signal, and disabled by sending ``SIGUSR2`` (see ``kill(1)``). The blackbox will be written after a crash, assertion failure, or ``SIGTRAP`` signal. See :ref:`PCMK_debug ` for allowed subsystems. Example: ``PCMK_blackbox="pacemakerd,pacemaker-execd"`` * - .. _pcmk_trace_blackbox: .. index:: pair: node option; PCMK_trace_blackbox PCMK_trace_blackbox - :ref:`enumeration ` - - *Advanced Use Only:* Write a blackbox whenever the message at the specified function and line is logged. Multiple entries may be comma- separated. Example: ``PCMK_trace_blackbox="remote.c:144,remote.c:149"`` * - .. _pcmk_node_start_state: .. index:: pair: node option; PCMK_node_start_state PCMK_node_start_state - :ref:`enumeration ` - default - By default, the local host will join the cluster in an online or standby state when Pacemaker first starts depending on whether it was previously put into standby mode. If this variable is set to ``standby`` or ``online``, it will force the local host to join in the specified state. * - .. _pcmk_node_action_limit: .. index:: pair: node option; PCMK_node_action_limit PCMK_node_action_limit - :ref:`nonnegative integer ` - - If set, this overrides the :ref:`node-action-limit ` cluster option on this node to specify the maximum number of jobs that can be scheduled on this node (or 0 to use twice the number of CPU cores). * - .. _pcmk_fail_fast: .. index:: pair: node option; PCMK_fail_fast PCMK_fail_fast - :ref:`boolean ` - no - By default, if a Pacemaker subsystem crashes, the main ``pacemakerd`` process will attempt to restart it. If this variable is set to ``yes``, ``pacemakerd`` will panic the local host instead. * - .. _pcmk_panic_action: .. index:: pair: node option; PCMK_panic_action PCMK_panic_action - :ref:`enumeration ` - reboot - Pacemaker will panic the local host under certain conditions. By default, this means rebooting the host. This variable can change that behavior: if ``crash``, trigger a kernel crash (useful if you want a kernel dump to investigate); if ``sync-reboot`` or ``sync-crash``, synchronize filesystems before rebooting the host or triggering a kernel crash. The sync values are more likely to preserve log messages, but with the risk that the host may be left active if the synchronization hangs. * - .. _pcmk_remote_address: .. index:: pair: node option; PCMK_remote_address PCMK_remote_address - :ref:`text ` - - By default, if the :ref:`Pacemaker Remote ` service is run on the local node, it will listen for connections on all IP addresses. This may be set to one address to listen on instead, as a resolvable hostname or as a numeric IPv4 or IPv6 address. When resolving names or listening on all addresses, IPv6 will be preferred if available. When listening on an IPv6 address, IPv4 clients will be supported via IPv4-mapped IPv6 addresses. Example: ``PCMK_remote_address="192.0.2.1"`` * - .. _pcmk_remote_port: .. index:: pair: node option; PCMK_remote_port PCMK_remote_port - :ref:`port ` - 3121 - Use this TCP port number for :ref:`Pacemaker Remote ` node connections. This value must be the same on all nodes. * - .. _pcmk_ca_file: .. index:: pair: node option; PCMK_ca_file PCMK_ca_file - :ref:`text ` - - The location of a file containing trusted Certificate Authorities, used to verify client or server certificates. This file must be in PEM format and must be readable by Pacemaker daemons (that is, it must allow read permissions to either the |CRM_DAEMON_USER| user or the |CRM_DAEMON_GROUP| group). If set, along with :ref:`PCMK_key_file ` and :ref:`PCMK_cert_file `, X509 authentication will be enabled for :ref:`Pacemaker Remote ` and remote CIB connections. Example: ``PCMK_ca_file="/etc/pacemaker/ca.cert.pem"`` * - .. _pcmk_cert_file: .. index:: pair: node option; PCMK_cert_file PCMK_cert_file - :ref:`text ` - - The location of a file containing the signed certificate for the server side of the connection. This file must be in PEM format and must be readable by Pacemaker daemons (that is, it must allow read permissions to either the |CRM_DAEMON_USER| user or the |CRM_DAEMON_GROUP| group). If set, along with :ref:`PCMK_ca_file ` and :ref:`PCMK_key_file `, X509 authentication will be enabled for :ref:`Pacemaker Remote ` and remote CIB connections. Example: ``PCMK_cert_file="/etc/pacemaker/server.cert.pem"`` * - .. _pcmk_crl_file: .. index:: pair: node option; PCMK_crl_file PCMK_crl_file - :ref:`text ` - - The location of a Certificate Revocation List file, in PEM format. This setting is optional for X509 authentication. Example: ``PCMK_cr1_file="/etc/pacemaker/crl.pem"`` * - .. _pcmk_key_file: .. index:: pair: node option; PCMK_key_file PCMK_key_file - :ref:`text ` - - The location of a file containing the private key for the matching :ref:`PCMK_cert_file `, in PEM format. This file must be readble by Pacemaker daemons (that is, it must allow read permissions to either the |CRM_DAEMON_USER| user or the |CRM_DAEMON_GROUP| group). If set, along with :ref:`PCMK_ca_file ` and :ref:`PCMK_cert_file `, X509 authentication will be enabled for :ref:`Pacemaker Remote ` and remote CIB connections. Example: ``PCMK_key_file="/etc/pacemaker/server.key.pem"`` * - .. _pcmk_authkey_location: .. index:: pair: node option; PCMK_authkey_location PCMK_authkey_location - :ref:`text ` - |PCMK_AUTHKEY_FILE| - As an alternative to using X509 authentication for :ref:`Pacemaker Remote ` connections, use the contents of this file as the authorization key. This file must be readable by Pacemaker daemons (that is, it must allow read permissions to either the |CRM_DAEMON_USER| user or the |CRM_DAEMON_GROUP| group), and its contents must be identical on all nodes. This is an alternative to using X509 certificates. * - .. _pcmk_remote_pid1: .. index:: pair: node option; PCMK_remote_pid1 PCMK_remote_pid1 - :ref:`enumeration ` - default - *Advanced Use Only:* When a bundle resource's ``run-command`` option is left to default, :ref:`Pacemaker Remote ` runs as PID 1 in the bundle's containers. When it does so, it loads environment variables from the container's |PCMK_INIT_ENV_FILE| and performs the PID 1 responsibility of reaping dead subprocesses. This option controls whether those actions are performed when Pacemaker Remote is not running as PID 1. It is intended primarily for developer testing but can be useful when ``run-command`` is set to a separate, custom PID 1 process that launches Pacemaker Remote. * ``full``: Pacemaker Remote loads environment variables from |PCMK_INIT_ENV_FILE| and reaps dead subprocesses. * ``vars``: Pacemaker Remote loads environment variables from |PCMK_INIT_ENV_FILE| but does not reap dead subprocesses. * ``default``: Pacemaker Remote performs neither action. If Pacemaker Remote is running as PID 1, this option is ignored, and the behavior is the same as for ``full``. * - .. _pcmk_tls_priorities: .. index:: pair: node option; PCMK_tls_priorities PCMK_tls_priorities - :ref:`text ` - |PCMK__GNUTLS_PRIORITIES| - *Advanced Use Only:* These `GnuTLS cipher priorities `_ will be used for TLS connections (whether for :ref:`Pacemaker Remote ` connections or remote CIB access, when enabled). Pacemaker will append ``":+ANON-DH"`` for remote CIB access and ``":+DHE-PSK:+PSK"`` for Pacemaker Remote connections, as they are required for the respective functionality. Example: ``PCMK_tls_priorities="SECURE128:+SECURE192"`` * - .. _pcmk_dh_max_bits: .. index:: pair: node option; PCMK_dh_max_bits PCMK_dh_max_bits - :ref:`nonnegative integer ` - 0 (no maximum) - *Advanced Use Only:* Set an upper bound on the bit length of the prime number generated for Diffie-Hellman parameters needed by TLS connections. The default is no maximum. The server (:ref:`Pacemaker Remote ` daemon, or CIB manager configured to accept remote clients) will use this value to provide a ceiling for the value recommended by the GnuTLS library. The library will only accept a limited number of specific values, which vary by library version, so setting these is recommended only when required for compatibility with specific client versions. Clients do not use ``PCMK_dh_max_bits``. * - .. _pcmk_ipc_type: .. index:: pair: node option; PCMK_ipc_type PCMK_ipc_type - :ref:`enumeration ` - shared-mem - *Advanced Use Only:* Force use of a particular IPC method. Allowed values: * ``shared-mem`` * ``socket`` * ``posix`` * ``sysv`` * - .. _pcmk_cluster_type: .. index:: pair: node option; PCMK_cluster_type PCMK_cluster_type - :ref:`enumeration ` - corosync - *Advanced Use Only:* Specify the cluster layer to be used. If unset, Pacemaker will detect and use a supported cluster layer, if available. Currently, ``"corosync"`` is the only supported cluster layer. If multiple layers are supported in the future, this will allow overriding Pacemaker's automatic detection to select a specific one. * - .. _pcmk_schema_directory: .. index:: pair: node option; PCMK_schema_directory PCMK_schema_directory - :ref:`text ` - |PCMK_SCHEMA_DIR| - *Advanced Use Only:* Specify an alternate location for RNG schemas and XSL transforms. * - .. _pcmk_remote_schema_directory: .. index:: pair: node option; PCMK_remote_schema_directory PCMK_remote_schema_directory - :ref:`text ` - |PCMK__REMOTE_SCHEMA_DIR| - *Advanced Use Only:* Specify an alternate location on :ref:`Pacemaker Remote ` nodes for storing newer RNG schemas and XSL transforms fetched from the cluster. * - .. _pcmk_valgrind_enabled: .. index:: pair: node option; PCMK_valgrind_enabled PCMK_valgrind_enabled - :ref:`enumeration ` - no - *Advanced Use Only:* Whether subsystem daemons should be run under ``valgrind``. Allowed values are the same as for ``PCMK_debug``. * - .. _pcmk_callgrind_enabled: .. index:: pair: node option; PCMK_callgrind_enabled PCMK_callgrind_enabled - :ref:`enumeration ` - no - *Advanced Use Only:* Whether subsystem daemons should be run under ``valgrind`` with the ``callgrind`` tool enabled. Allowed values are the same as for ``PCMK_debug``. * - .. _sbd_sync_resource_startup: .. index:: pair: node option; SBD_SYNC_RESOURCE_STARTUP SBD_SYNC_RESOURCE_STARTUP - :ref:`boolean ` - - If true, ``pacemakerd`` waits for a ping from ``sbd`` during startup before starting other Pacemaker daemons, and during shutdown after stopping other Pacemaker daemons but before exiting. Default value is set based on the ``--with-sbd-sync-default`` configure script option. * - .. _sbd_watchdog_timeout: .. index:: pair: node option; SBD_WATCHDOG_TIMEOUT SBD_WATCHDOG_TIMEOUT - :ref:`duration ` - - If the ``stonith-watchdog-timeout`` cluster property is set to a negative or invalid value, use double this value as the default if positive, or use 0 as the default otherwise. This value must be greater than the value of ``stonith-watchdog-timeout`` if both are set. * - .. _valgrind_opts: .. index:: pair: node option; VALGRIND_OPTS VALGRIND_OPTS - :ref:`text ` - - *Advanced Use Only:* Pass these options to valgrind, when enabled (see ``valgrind(1)``). ``"--vgdb=no"`` should usually be specified because ``pacemaker-execd`` can lower privileges when executing commands, which would otherwise leave a bunch of unremovable files in ``/tmp``. diff --git a/doc/sphinx/Pacemaker_Explained/nodes.rst b/doc/sphinx/Pacemaker_Explained/nodes.rst index e88e63a10e..5b8e09e206 100644 --- a/doc/sphinx/Pacemaker_Explained/nodes.rst +++ b/doc/sphinx/Pacemaker_Explained/nodes.rst @@ -1,613 +1,613 @@ .. index:: single: node Nodes ----- Pacemaker supports two basic types of nodes: *cluster nodes* and *Pacemaker Remote nodes*. .. index:: single: node; cluster node Cluster nodes _____________ Cluster nodes run Corosync and all Pacemaker components. They may run cluster resources, run all Pacemaker command-line tools, execute fencing actions, count toward cluster quorum, and serve as the cluster's Designated Controller (DC). Every cluster must have at least one cluster node. Scalability is limited by the cluster layer to around 32 cluster nodes. Host Clock Considerations ######################### In general, Pacemaker does not rely on time or time zones being synchronized across nodes. However, if the configuration uses date/time-based :ref:`rules `, synchronization is a good idea, otherwise the rules will evaluate differently depending on which node is the Designated Controller (DC). Also, synchronization is greatly helpful when comparing logs across multiple nodes for problem investigation. If a node's clock jumps forward, you may see relatively minor issues such as various timeouts suddenly being considered expired. If a node's clock jumps backward, more serious problems may occur, so this should be avoided. If the host clock is adjusted at boot, and Pacemaker is enabled at boot, Pacemaker's start should be ordered after the clock adjustment. When run under systemd, Pacemaker will automatically order itself after ``time-sync.target``. However, depending on the local setup, you may need to enable an additional service (for example, ``chronyd-wait.service``) for that to be effective, or write your own workaround (for example, see the discussion on `systemd issue#5097 `_. .. _pacemaker_remote: .. index:: pair: node; Pacemaker Remote Pacemaker Remote nodes ______________________ Pacemaker Remote nodes do not run Corosync or the usual Pacemaker components. Instead, they run only the *remote executor* (``pacemaker-remoted``), which waits for Pacemaker on a cluster node to give it instructions. They may run cluster resources and most command-line tools, but cannot perform other functions of full cluster nodes such as fencing execution, quorum voting, or DC eligibility. There is no hard limit on the number of Pacemaker Remote nodes. .. NOTE:: *Remote* in this document has nothing to do with physical proximity and instead refers to the node not being a member of the underlying Corosync cluster. Pacemaker Remote nodes are subject to the same latency requirements as cluster nodes, which means they are typically in the same data center. There are three types of Pacemaker Remote nodes: * A *remote node* boots outside Pacemaker control, and is typically a physical host. The connection to the remote node is managed as a :ref:`special type of resource ` configured by the user. * A *guest node* is a virtual machine or container configured to run Pacemaker's remote executor when launched, and is launched and managed by the cluster as a standard resource configured by the user with :ref:`special options `. * A *bundle node* is a guest node created for a container that is launched and managed by the cluster as part of a :ref:`bundle ` resource configured by the user. .. NOTE:: It is important to distinguish the various roles a virtual machine can serve in Pacemaker clusters: * A virtual machine can run the full cluster stack, in which case it is a cluster node and is not itself managed by the cluster. * A virtual machine can be managed by the cluster as a simple resource, without the cluster having any awareness of the services running within it. The virtual machine is *opaque* to the cluster. * A virtual machine can be a guest node, allowing the cluster to manage both the virtual machine and resources running within it. The virtual machine is *transparent* to the cluster. Defining a Node _______________ Each cluster node will have an entry in the ``nodes`` section containing at least an ID and a name. A cluster node's ID is defined by the cluster layer (Corosync). .. topic:: **Example Corosync cluster node entry** .. code-block:: xml Pacemaker Remote nodes are defined by a resource in the ``resources`` section. Remote nodes and guest nodes may optionally have an entry in the ``nodes`` section, primarily for permanent :ref:`node attributes `. Normally, the user should let the cluster populate the ``nodes`` section automatically. .. index:: single: node; name .. _node_name: Where Pacemaker Gets the Node Name ################################## The name that Pacemaker uses for a node in the configuration does not have to be the same as its local hostname. Pacemaker uses the following for a cluster node's name, in order of most preferred first: * The value of ``name`` in the ``nodelist`` section of ``corosync.conf`` (``nodeid`` must also be explicitly set there in order for Pacemaker to associate the name with the node) * The value of ``ring0_addr`` in the ``nodelist`` section of ``corosync.conf`` * The local hostname (value of ``uname -n``) A Pacemaker Remote node's name is defined in its resource configuration. If the cluster is running, the ``crm_node -n`` command will display the local node's name as used by the cluster. If a Corosync ``nodelist`` is used, ``crm_node --name-for-id`` with a Corosync node ID will display the name used by the node with the given Corosync ``nodeid``, for example: .. code-block:: none crm_node --name-for-id 2 .. index:: single: node; quorum-only single: quorum-only node Quorum-only Nodes _________________ One popular cluster design uses an even number of cluster nodes (often 2), with an additional lightweight host that contributes to providing quorum but cannot run resources. With Pacemaker, this can be achieved in either of two ways: * When Corosync is used as the underlying cluster layer, the lightweight host can run `qdevice `_ instead of Corosync and Pacemaker. * The lightweight host can be configured as a Pacemaker cluster node, and a :ref:`location constraint ` can be configured for the node with ``score`` set to ``-INFINITY``, ``rsc-pattern`` set to ``.*``, and ``resource-discovey`` set to ``never``. .. index:: single: node; attribute single: node attribute .. _node_attributes: Node Attributes _______________ Pacemaker allows node-specific values to be specified using *node attributes*. A node attribute has a name, and may have a distinct value for each node. Node attributes come in two types, *permanent* and *transient*. Permanent node attributes are kept within the ``node`` entry, and keep their values even if the cluster restarts on a node. Transient node attributes are kept in the CIB's ``status`` section, and go away when the cluster stops on the node. While certain node attributes have specific meanings to the cluster, they are mainly intended to allow administrators and resource agents to track any information desired. For example, an administrator might choose to define node attributes for how much RAM and disk space each node has, which OS each uses, or which server room rack each node is in. Users can configure :ref:`rules` that use node attributes to affect where resources are placed. Setting and querying node attributes #################################### Node attributes can be set and queried using the ``crm_attribute`` and ``attrd_updater`` commands, so that the user does not have to deal with XML configuration directly. Here is an example command to set a permanent node attribute, and the XML configuration that would be generated: .. topic:: **Result of using crm_attribute to specify which kernel pcmk-1 is running** .. code-block:: none # crm_attribute --type nodes --node pcmk-1 --name kernel --update $(uname -r) .. code-block:: xml To read back the value that was just set: .. code-block:: none # crm_attribute --type nodes --node pcmk-1 --name kernel --query scope=nodes name=kernel value=3.10.0-862.14.4.el7.x86_64 The ``--type nodes`` indicates that this is a permanent node attribute; ``--type status`` would indicate a transient node attribute. .. warning:: Attribute values with newline or tab characters are currently displayed with newlines as ``"\n"`` and tabs as ``"\t"``, when ``crm_attribute`` or ``attrd_updater`` query commands use ``--output-as=text`` or leave ``--output-as`` unspecified: .. code-block:: none # crm_attribute -N node1 -n test_attr -v "$(echo -e "a\nb\tc")" -t status # crm_attribute -N node1 -n test_attr --query -t status scope=status name=test_attr value=a\nb\tc This format is deprecated. In a future release, the values will be displayed with literal whitespace characters: .. code-block:: none # crm_attribute -N node1 -n test_attr --query -t status scope=status name=test_attr value=a b c Users should either avoid attribute values with newlines and tabs, or ensure that they can handle both formats. However, it's best to use ``--output-as=xml`` when parsing attribute values from output. Newlines, tabs, and special characters are replaced with XML character references that a conforming XML processor can recognize and convert to literals *(since 2.1.8)*: .. code-block:: none # crm_attribute -N node1 -n test_attr --query -t status --output-as=xml Special node attributes ####################### Certain node attributes have special meaning to the cluster. Node attribute names beginning with ``#`` are considered reserved for these special attributes. Some special attributes do not start with ``#``, for historical reasons. Certain special attributes are set automatically by the cluster, should never be modified directly, and can be used only within :ref:`rules`; these are listed under :ref:`built-in node attributes `. For true/false values, the cluster considers a value of "1", "y", "yes", "on", or "true" (case-insensitively) to be true, "0", "n", "no", "off", "false", or unset to be false, and anything else to be an error. .. table:: **Node attributes with special significance** :class: longtable - :widths: 1 2 + :widths: 30 70 +----------------------------+-----------------------------------------------------+ | Name | Description | +============================+=====================================================+ | fail-count-* | .. index:: | | | pair: node attribute; fail-count | | | | | | Attributes whose names start with | | | ``fail-count-`` are managed by the cluster | | | to track how many times particular resource | | | operations have failed on this node. These | | | should be queried and cleared via the | | | ``crm_failcount`` or | | | ``crm_resource --cleanup`` commands rather | | | than directly. | +----------------------------+-----------------------------------------------------+ | last-failure-* | .. index:: | | | pair: node attribute; last-failure | | | | | | Attributes whose names start with | | | ``last-failure-`` are managed by the cluster | | | to track when particular resource operations | | | have most recently failed on this node. | | | These should be cleared via the | | | ``crm_failcount`` or | | | ``crm_resource --cleanup`` commands rather | | | than directly. | +----------------------------+-----------------------------------------------------+ | maintenance | .. _node_maintenance: | | | | | | .. index:: | | | pair: node attribute; maintenance | | | | | | If true, the cluster will not start or stop any | | | resources on this node. Any resources active on the | | | node become unmanaged, and any recurring operations | | | for those resources (except those specifying | | | ``role`` as ``Stopped``) will be paused. The | | | :ref:`maintenance-mode ` cluster | | | option, if true, overrides this. If this attribute | | | is true, it overrides the | | | :ref:`is-managed ` and | | | :ref:`maintenance ` | | | meta-attributes of affected resources and | | | :ref:`enabled ` meta-attribute for | | | affected recurring actions. Pacemaker should not be | | | restarted on a node that is in single-node | | | maintenance mode. | +----------------------------+-----------------------------------------------------+ | probe_complete | .. index:: | | | pair: node attribute; probe_complete | | | | | | This is managed by the cluster to detect | | | when nodes need to be reprobed, and should | | | never be used directly. | +----------------------------+-----------------------------------------------------+ | resource-discovery-enabled | .. index:: | | | pair: node attribute; resource-discovery-enabled | | | | | | If the node is a remote node, fencing is enabled, | | | and this attribute is explicitly set to false | | | (unset means true in this case), resource discovery | | | (probes) will not be done on this node. This is | | | highly discouraged; the ``resource-discovery`` | | | location constraint property is preferred for this | | | purpose. | +----------------------------+-----------------------------------------------------+ | shutdown | .. index:: | | | pair: node attribute; shutdown | | | | | | This is managed by the cluster to orchestrate the | | | shutdown of a node, and should never be used | | | directly. | +----------------------------+-----------------------------------------------------+ | site-name | .. index:: | | | pair: node attribute; site-name | | | | | | If set, this will be used as the value of the | | | ``#site-name`` node attribute used in rules. (If | | | not set, the value of the ``cluster-name`` cluster | | | option will be used as ``#site-name`` instead.) | +----------------------------+-----------------------------------------------------+ | standby | .. index:: | | | pair: node attribute; standby | | | | | | If true, the node is in standby mode. This is | | | typically set and queried via the ``crm_standby`` | | | command rather than directly. | +----------------------------+-----------------------------------------------------+ | terminate | .. index:: | | | pair: node attribute; terminate | | | | | | If the value is true or begins with any nonzero | | | number, the node will be fenced. This is typically | | | set by tools rather than directly. | +----------------------------+-----------------------------------------------------+ | #digests-* | .. index:: | | | pair: node attribute; #digests | | | | | | Attributes whose names start with ``#digests-`` are | | | managed by the cluster to detect when | | | :ref:`unfencing` needs to be redone, and should | | | never be used directly. | +----------------------------+-----------------------------------------------------+ | #node-unfenced | .. index:: | | | pair: node attribute; #node-unfenced | | | | | | When the node was last unfenced (as seconds since | | | the epoch). This is managed by the cluster and | | | should never be used directly. | +----------------------------+-----------------------------------------------------+ .. index:: single: node; health .. _node-health: Tracking Node Health ____________________ A node may be functioning adequately as far as cluster membership is concerned, and yet be "unhealthy" in some respect that makes it an undesirable location for resources. For example, a disk drive may be reporting SMART errors, or the CPU may be highly loaded. Pacemaker offers a way to automatically move resources off unhealthy nodes. .. index:: single: node attribute; health Node Health Attributes ###################### Pacemaker will treat any node attribute whose name starts with ``#health`` as an indicator of node health. Node health attributes may have one of the following values: .. table:: **Allowed Values for Node Health Attributes** - :widths: 1 4 + :widths: 25 75 +------------+--------------------------------------------------------------+ | Value | Intended significance | +============+==============================================================+ | ``red`` | .. index:: | | | single: red; node health attribute value | | | single: node attribute; health (red) | | | | | | This indicator is unhealthy | +------------+--------------------------------------------------------------+ | ``yellow`` | .. index:: | | | single: yellow; node health attribute value | | | single: node attribute; health (yellow) | | | | | | This indicator is close to unhealthy (whether worsening or | | | recovering) | +------------+--------------------------------------------------------------+ | ``green`` | .. index:: | | | single: green; node health attribute value | | | single: node attribute; health (green) | | | | | | This indicator is healthy | +------------+--------------------------------------------------------------+ | *integer* | .. index:: | | | single: score; node health attribute value | | | single: node attribute; health (score) | | | | | | A numeric score to apply to all resources on this node (0 or | | | positive is healthy, negative is unhealthy) | +------------+--------------------------------------------------------------+ .. note:: A health attribute may technically be transient or permanent, but generally only transient makes sense. .. note:: ``red``, ``yellow``, and ``green`` function as aliases for particular numeric scores as described later. .. index:: pair: cluster option; node-health-strategy Node Health Strategy #################### Pacemaker assigns a node health score to each node, as the sum of the values of all its node health attributes. This score will be used as a location constraint applied to this node for all resources. The ``node-health-strategy`` cluster option controls how Pacemaker responds to changes in node health attributes, and how it translates ``red``, ``yellow``, and ``green`` to scores. Allowed values are: .. table:: **Node Health Strategies** - :widths: 1 4 + :widths: 25 75 +----------------+----------------------------------------------------------+ | Value | Effect | +================+==========================================================+ | none | .. index:: | | | single: node-health-strategy; none | | | single: none; node-health-strategy value | | | | | | Do not track node health attributes at all. | +----------------+----------------------------------------------------------+ | migrate-on-red | .. index:: | | | single: node-health-strategy; migrate-on-red | | | single: migrate-on-red; node-health-strategy value | | | | | | Assign the value of ``-INFINITY`` to ``red``, and 0 to | | | ``yellow`` and ``green``. This will cause all resources | | | to move off the node if any attribute is ``red``. | +----------------+----------------------------------------------------------+ | only-green | .. index:: | | | single: node-health-strategy; only-green | | | single: only-green; node-health-strategy value | | | | | | Assign the value of ``-INFINITY`` to ``red`` and | | | ``yellow``, and 0 to ``green``. This will cause all | | | resources to move off the node if any attribute is | | | ``red`` or ``yellow``. | +----------------+----------------------------------------------------------+ | progressive | .. index:: | | | single: node-health-strategy; progressive | | | single: progressive; node-health-strategy value | | | | | | Assign the value of the ``node-health-red`` cluster | | | option to ``red``, the value of ``node-health-yellow`` | | | to ``yellow``, and the value of ``node-health-green`` to | | | ``green``. Each node is additionally assigned a score of | | | ``node-health-base`` (this allows resources to start | | | even if some attributes are ``yellow``). This strategy | | | gives the administrator finer control over how important | | | each value is. | +----------------+----------------------------------------------------------+ | custom | .. index:: | | | single: node-health-strategy; custom | | | single: custom; node-health-strategy value | | | | | | Track node health attributes using the same values as | | | ``progressive`` for ``red``, ``yellow``, and ``green``, | | | but do not take them into account. The administrator is | | | expected to implement a policy by defining :ref:`rules` | | | referencing node health attributes. | +----------------+----------------------------------------------------------+ Exempting a Resource from Health Restrictions ############################################# If you want a resource to be able to run on a node even if its health score would otherwise prevent it, set the resource's ``allow-unhealthy-nodes`` meta-attribute to ``true`` *(available since 2.1.3)*. This is particularly useful for node health agents, to allow them to detect when the node becomes healthy again. If you configure a health agent without this setting, then the health agent will be banned from an unhealthy node, and you will have to investigate and clear the health attribute manually once it is healthy to allow resources on the node again. If you want the meta-attribute to apply to a clone, it must be set on the clone itself, not on the resource being cloned. Configuring Node Health Agents ############################## Since Pacemaker calculates node health based on node attributes, any method that sets node attributes may be used to measure node health. The most common are resource agents and custom daemons. Pacemaker provides examples that can be used directly or as a basis for custom code. The ``ocf:pacemaker:HealthCPU``, ``ocf:pacemaker:HealthIOWait``, and ``ocf:pacemaker:HealthSMART`` resource agents set node health attributes based on CPU and disk status. To take advantage of this feature, add the resource to your cluster (generally as a cloned resource with a recurring monitor action, to continually check the health of all nodes). For example: .. topic:: Example HealthIOWait resource configuration .. code-block:: xml The resource agents use ``attrd_updater`` to set proper status for each node running this resource, as a node attribute whose name starts with ``#health`` (for ``HealthIOWait``, the node attribute is named ``#health-iowait``). When a node is no longer faulty, you can force the cluster to make it available to take resources without waiting for the next monitor, by setting the node health attribute to green. For example: .. topic:: **Force node1 to be marked as healthy** .. code-block:: none # attrd_updater --name "#health-iowait" --update "green" --node "node1" diff --git a/doc/sphinx/Pacemaker_Explained/operations.rst b/doc/sphinx/Pacemaker_Explained/operations.rst index b5488268e8..10a7e12c3c 100644 --- a/doc/sphinx/Pacemaker_Explained/operations.rst +++ b/doc/sphinx/Pacemaker_Explained/operations.rst @@ -1,701 +1,701 @@ .. index:: single: resource; action single: resource; operation .. _operation: Resource Operations ------------------- *Operations* are actions the cluster can perform on a resource by calling the resource agent. Resource agents must support certain common operations such as start, stop, and monitor, and may implement any others. Operations may be explicitly configured for two purposes: to override defaults for options (such as timeout) that the cluster will use whenever it initiates the operation, and to run an operation on a recurring basis (for example, to monitor the resource for failure). .. topic:: An OCF resource with a non-default start timeout .. code-block:: xml Pacemaker identifies operations by a combination of name and interval, so this combination must be unique for each resource. That is, you should not configure two operations for the same resource with the same name and interval. .. _operation_properties: Operation Properties #################### The ``id``, ``name``, ``interval``, and ``role`` operation properties may be specified only as XML attributes of the ``op`` element. Other operation properties may be specified in any of the following ways, from highest precedence to lowest: * directly in the ``op`` element as an XML attribute * in an ``nvpair`` element within a ``meta_attributes`` element within the ``op`` element * in an ``nvpair`` element within a ``meta_attributes`` element within :ref:`operation defaults ` If not specified, the default from the table below is used. .. list-table:: **Operation Properties** :class: longtable - :widths: 2 2 3 4 + :widths: 17 13 30 40 :header-rows: 1 * - Name - Type - Default - Description * - .. _op_id: .. index:: pair: op; id single: id; action property single: action; property, id id - :ref:`id ` - - A unique identifier for the XML element *(required)* * - .. _op_name: .. index:: pair: op; name single: name; action property single: action; property, name name - :ref:`text ` - - An action name supported by the resource agent *(required)* * - .. _op_interval: .. index:: pair: op; interval single: interval; action property single: action; property, interval interval - :ref:`duration ` - 0 - If this is a positive value, Pacemaker will schedule recurring instances of this operation at the given interval (which makes sense only with :ref:`name ` set to :ref:`monitor `). If this is 0, Pacemaker will apply other properties configured for this operation to instances that are scheduled as needed during normal cluster operation. *(required)* * - .. _op_description: .. index:: pair: op; description single: description; action property single: action; property, description description - :ref:`text ` - - Arbitrary text for user's use (ignored by Pacemaker) * - .. _op_role: .. index:: pair: op; role single: role; action property single: action; property, role role - :ref:`enumeration ` - - If this is set, the operation configuration applies only on nodes where the cluster expects the resource to be in the specified role. This makes sense only for recurring monitors. Allowed values: ``Started``, ``Stopped``, and in the case of :ref:`promotable clone resources `, ``Unpromoted`` and ``Promoted``. * - .. _op_timeout: .. index:: pair: op; timeout single: timeout; action property single: action; property, timeout timeout - :ref:`timeout ` - 20s - If resource agent execution does not complete within this amount of time, the action will be considered failed. **Note:** timeouts for fencing agents are handled specially (see the :ref:`fencing` chapter). * - .. _op_on_fail: .. index:: pair: op; on-fail single: on-fail; action property single: action; property, on-fail on-fail - :ref:`enumeration ` - * If ``name`` is ``stop``: ``fence`` if :ref:`stonith-enabled ` is true, otherwise ``block`` * If ``name`` is ``demote``: ``on-fail`` of the ``monitor`` action with ``role`` set to ``Promoted``, if present, enabled, and configured to a value other than ``demote``, or ``restart`` otherwise * Otherwise: ``restart`` - How the cluster should respond to a failure of this action. Allowed values: * ``ignore:`` Pretend the resource did not fail * ``block:`` Do not perform any further operations on the resource * ``stop:`` Stop the resource and leave it stopped * ``demote:`` Demote the resource, without a full restart. This is valid only for ``promote`` actions, and for ``monitor`` actions with both a nonzero ``interval`` and ``role`` set to ``Promoted``; for any other action, a configuration error will be logged, and the default behavior will be used. *(since 2.0.5)* * ``restart:`` Stop the resource, and start it again if allowed (possibly on a different node) * ``fence:`` Fence the node on which the resource failed * ``standby:`` Put the node on which the resource failed in standby mode (forcing *all* resources away) * - .. _op_enabled: .. index:: pair: op; enabled single: enabled; action property single: action; property, enabled enabled - :ref:`boolean ` - true - If ``false``, ignore this operation definition. This does not suppress all actions of this type, but is typically used to pause a recurring monitor. This can complement the resource being unmanaged (:ref:`is-managed ` set to ``false``), which does not stop recurring operations. Maintenance mode, which does stop configured monitors, overrides this setting. * - .. _op_interval_origin: .. index:: pair: op; interval-origin single: interval-origin; action property single: action; property, interval-origin interval-origin - :ref:`ISO 8601 ` - - If set for a recurring action, the action will be scheduled for this time plus a multiple of the action's interval, rather than immediately after the resource gains the monitored role. For example, you might schedule an in-depth monitor to run once per day outside business hours, by setting this to the desired time (on any date) and setting ``interval`` to ``24h``. At most one of ``interval-origin`` and ``start-delay`` may be set. * - .. _op_start_delay: .. index:: pair: op; start-delay single: start-delay; action property single: action; property, start-delay start-delay - :ref:`duration ` - - If set, the cluster will wait this long before running the action (for the first time, if recurring). This is an advanced option that should generally be avoided. It can be useful for a recurring monitor if a resource agent incorrectly returns success from start before the service is actually ready, and the agent can't be corrected, or for a start action if a service takes a very long time to start, and you don't want to block the cluster from responding to other events during that time. If this delay is longer than 5 minutes, the cluster will pretend that the action succeeded when it is first scheduled for the purpose of other actions needed, then act on the result when it actually runs. At most one of ``interval-origin`` and ``start-delay`` may be set. * - .. _op_record_pending: .. index:: pair: op; record-pending single: record-pending; action property single: action; property, record-pending record-pending - :ref:`boolean ` - true - Operation results are always recorded when the operation completes (successful or not). If this is ``true``, operations will also be recorded when initiated, so that status output can indicate that the operation is in progress. *(deprecated since 3.0.0)* .. note:: Only one action can be configured for any given combination of ``name`` and ``interval``. .. note:: When ``on-fail`` is set to ``demote``, recovery from failure by a successful demote causes the cluster to recalculate whether and where a new instance should be promoted. The node with the failure is eligible, so if promotion scores have not changed, it will be promoted again. There is no direct equivalent of ``migration-threshold`` for the promoted role, but the same effect can be achieved with a location constraint using a :ref:`rule ` with a node attribute expression for the resource's fail count. For example, to immediately ban the promoted role from a node with any failed promote or promoted instance monitor: .. code-block:: xml This example assumes that there is a promotable clone of the ``my_primitive`` resource (note that the primitive name, not the clone name, is used in the rule), and that there is a recurring 10-second-interval monitor configured for the promoted role (fail count attributes specify the interval in milliseconds). .. _s-resource-monitoring: Monitoring Resources for Failure ################################ When Pacemaker first starts a resource, it runs one-time ``monitor`` operations (referred to as *probes*) to ensure the resource is running where it's supposed to be, and not running where it's not supposed to be. (This behavior can be affected by the ``resource-discovery`` location constraint property.) Other than those initial probes, Pacemaker will *not* (by default) check that the resource continues to stay healthy [#]_. You must configure ``monitor`` operations explicitly to perform these checks. .. topic:: An OCF resource with a recurring health check .. code-block:: xml By default, a ``monitor`` operation will ensure that the resource is running where it is supposed to. The ``target-role`` property can be used for further checking. For example, if a resource has one ``monitor`` operation with ``interval=10 role=Started`` and a second ``monitor`` operation with ``interval=11 role=Stopped``, the cluster will run the first monitor on any nodes it thinks *should* be running the resource, and the second monitor on any nodes that it thinks *should not* be running the resource (for the truly paranoid, who want to know when an administrator manually starts a service by mistake). .. note:: Currently, monitors with ``role=Stopped`` are not implemented for :ref:`clone ` resources. Custom Recurring Operations ########################### Typically, only ``monitor`` operations should be configured as recurring. However, it is possible to implement a custom action name in an OCF agent and then configure that as a recurring operation. This could be useful, for example, to run a report, rotate a log, or clean temporary files related to a particular service. Failures of custom recurring operations will be ignored by the cluster and will not be reported in cluster status *(since 3.0.0; previously, they would be treated like failed monitors)*. A fail count and last failure timestamp will be recorded as transient node attributes, and those node attributes will be erased by the ``crm_resource --cleanup`` command. .. _s-operation-defaults: Setting Global Defaults for Operations ###################################### You can change the global default values for operation properties in a given cluster. These are defined in an ``op_defaults`` section of the CIB's ``configuration`` section, and can be set with ``crm_attribute``. For example, .. code-block:: none # crm_attribute --type op_defaults --name timeout --update 20s would default each operation's ``timeout`` to 20 seconds. If an operation's definition also includes a value for ``timeout``, then that value would be used for that operation instead. When Implicit Operations Take a Long Time ######################################### The cluster will always perform a number of implicit operations: ``start``, ``stop`` and a non-recurring ``monitor`` operation used at startup to check whether the resource is already active. If one of these is taking too long, then you can create an entry for them and specify a longer timeout. .. topic:: An OCF resource with custom timeouts for its implicit actions .. code-block:: xml Multiple Monitor Operations ########################### Provided no two operations (for a single resource) have the same name and interval, you can have as many ``monitor`` operations as you like. In this way, you can do a superficial health check every minute and progressively more intense ones at higher intervals. To tell the resource agent what kind of check to perform, you need to provide each monitor with a different value for a common parameter. The OCF standard creates a special parameter called ``OCF_CHECK_LEVEL`` for this purpose and dictates that it is "made available to the resource agent without the normal ``OCF_RESKEY`` prefix". Whatever name you choose, you can specify it by adding an ``instance_attributes`` block to the ``op`` tag. It is up to each resource agent to look for the parameter and decide how to use it. .. topic:: An OCF resource with two recurring health checks, performing different levels of checks specified via ``OCF_CHECK_LEVEL``. .. code-block:: xml Disabling a Monitor Operation ############################# The easiest way to stop a recurring monitor is to just delete it. However, there can be times when you only want to disable it temporarily. In such cases, simply add ``enabled=false`` to the operation's definition. .. topic:: Example of an OCF resource with a disabled health check .. code-block:: xml This can be achieved from the command line by executing: .. code-block:: none # cibadmin --modify --xml-text '' Once you've done whatever you needed to do, you can then re-enable it with .. code-block:: none # cibadmin --modify --xml-text '' .. index:: single: resource; failure recovery single: operation; failure recovery .. _failure-handling: Handling Resource Failure ######################### By default, Pacemaker will attempt to recover failed resources by restarting them. However, failure recovery is highly configurable. .. index:: single: resource; failure count single: operation; failure count Failure Counts ______________ Pacemaker tracks resource failures for each combination of node, resource, and operation (start, stop, monitor, etc.). You can query the fail count for a particular node, resource, and/or operation using the ``crm_failcount`` command. For example, to see how many times the 10-second monitor for ``myrsc`` has failed on ``node1``, run: .. code-block:: none # crm_failcount --query -r myrsc -N node1 -n monitor -I 10s If you omit the node, ``crm_failcount`` will use the local node. If you omit the operation and interval, ``crm_failcount`` will display the sum of the fail counts for all operations on the resource. You can use ``crm_resource --cleanup`` or ``crm_failcount --delete`` to clear fail counts. For example, to clear the above monitor failures, run: .. code-block:: none # crm_resource --cleanup -r myrsc -N node1 -n monitor -I 10s If you omit the resource, ``crm_resource --cleanup`` will clear failures for all resources. If you omit the node, it will clear failures on all nodes. If you omit the operation and interval, it will clear the failures for all operations on the resource. .. note:: Even when cleaning up only a single operation, all failed operations will disappear from the status display. This allows us to trigger a re-check of the resource's current status. Higher-level tools may provide other commands for querying and clearing fail counts. The ``crm_mon`` tool shows the current cluster status, including any failed operations. To see the current fail counts for any failed resources, call ``crm_mon`` with the ``--failcounts`` option. This shows the fail counts per resource (that is, the sum of any operation fail counts for the resource). .. index:: single: migration-threshold; resource meta-attribute single: resource; migration-threshold Failure Response ________________ Normally, if a running resource fails, pacemaker will try to stop it and start it again. Pacemaker will choose the best location to start it each time, which may be the same node that it failed on. However, if a resource fails repeatedly, it is possible that there is an underlying problem on that node, and you might desire trying a different node in such a case. Pacemaker allows you to set your preference via the ``migration-threshold`` resource meta-attribute. [#]_ If you define ``migration-threshold`` to *N* for a resource, it will be banned from the original node after *N* failures there. .. note:: The ``migration-threshold`` is per *resource*, even though fail counts are tracked per *operation*. The operation fail counts are added together to compare against the ``migration-threshold``. By default, fail counts remain until manually cleared by an administrator using ``crm_resource --cleanup`` or ``crm_failcount --delete`` (hopefully after first fixing the failure's cause). It is possible to have fail counts expire automatically by setting the ``failure-timeout`` resource meta-attribute. .. important:: A successful operation does not clear past failures. If a recurring monitor operation fails once, succeeds many times, then fails again days later, its fail count is 2. Fail counts are cleared only by manual intervention or failure timeout. For example, setting ``migration-threshold`` to 2 and ``failure-timeout`` to ``60s`` would cause the resource to move to a new node after 2 failures, and allow it to move back (depending on stickiness and constraint scores) after one minute. .. note:: ``failure-timeout`` is measured since the most recent failure. That is, older failures do not individually time out and lower the fail count. Instead, all failures are timed out simultaneously (and the fail count is reset to 0) if there is no new failure for the timeout period. There are two exceptions to the migration threshold: when a resource either fails to start or fails to stop. If the cluster property ``start-failure-is-fatal`` is set to ``true`` (which is the default), start failures cause the fail count to be set to ``INFINITY`` and thus always cause the resource to move immediately. Stop failures are slightly different and crucial. If a resource fails to stop and fencing is enabled, then the cluster will fence the node in order to be able to start the resource elsewhere. If fencing is disabled, then the cluster has no way to continue and will not try to start the resource elsewhere, but will try to stop it again after any failure timeout or clearing. .. index:: single: reload single: reload-agent Reloading an Agent After a Definition Change ############################################ The cluster automatically detects changes to the configuration of active resources. The cluster's normal response is to stop the service (using the old definition) and start it again (with the new definition). This works, but some resource agents are smarter and can be told to use a new set of options without restarting. To take advantage of this capability, the resource agent must: * Implement the ``reload-agent`` action. What it should do depends completely on your application! .. note:: Resource agents may also implement a ``reload`` action to make the managed service reload its own *native* configuration. This is different from ``reload-agent``, which makes effective changes in the resource's *Pacemaker* configuration (specifically, the values of the agent's reloadable parameters). * Advertise the ``reload-agent`` operation in the ``actions`` section of its meta-data. * Set the ``reloadable`` attribute to 1 in the ``parameters`` section of its meta-data for any parameters eligible to be reloaded after a change. Once these requirements are satisfied, the cluster will automatically know to reload the resource (instead of restarting) when a reloadable parameter changes. .. note:: Metadata will not be re-read unless the resource needs to be started. If you edit the agent of an already active resource to set a parameter reloadable, the resource may restart the first time the parameter value changes. .. note:: If both a reloadable and non-reloadable parameter are changed simultaneously, the resource will be restarted. .. _live-migration: Migrating Resources ################### Normally, when the cluster needs to move a resource, it fully restarts the resource (that is, it stops the resource on the current node and starts it on the new node). However, some types of resources, such as many virtual machines, are able to move to another location without loss of state (often referred to as live migration or hot migration). In pacemaker, this is called live migration. Pacemaker can be configured to migrate a resource when moving it, rather than restarting it. Not all resources are able to migrate; see the :ref:`migration checklist ` below. Even those that can, won't do so in all situations. Conceptually, there are two requirements from which the other prerequisites follow: * The resource must be active and healthy at the old location; and * everything required for the resource to run must be available on both the old and new locations. The cluster is able to accommodate both *push* and *pull* migration models by requiring the resource agent to support two special actions: ``migrate_to`` (performed on the current location) and ``migrate_from`` (performed on the destination). In push migration, the process on the current location transfers the resource to the new location where is it later activated. In this scenario, most of the work would be done in the ``migrate_to`` action and, if anything, the activation would occur during ``migrate_from``. Conversely for pull, the ``migrate_to`` action is practically empty and ``migrate_from`` does most of the work, extracting the relevant resource state from the old location and activating it. There is no wrong or right way for a resource agent to implement migration, as long as it works. .. _migration_checklist: .. topic:: Migration Checklist * The resource may not be a clone. * The resource agent standard must be OCF. * The resource must not be in a failed or degraded state. * The resource agent must support ``migrate_to`` and ``migrate_from`` actions, and advertise them in its meta-data. * The resource must have the ``allow-migrate`` meta-attribute set to ``true`` (which is not the default). If an otherwise migratable resource depends on another resource via an ordering constraint, there are special situations in which it will be restarted rather than migrated. For example, if the resource depends on a clone, and at the time the resource needs to be moved, the clone has instances that are stopping and instances that are starting, then the resource will be restarted. The scheduler is not yet able to model this situation correctly and so takes the safer (if less optimal) path. Also, if a migratable resource depends on a non-migratable resource, and both need to be moved, the migratable resource will be restarted. .. rubric:: Footnotes .. [#] Currently, anyway. Automatic monitoring operations may be added in a future version of Pacemaker. .. [#] The naming of this option was perhaps unfortunate as it is easily confused with live migration, the process of moving a resource from one node to another without stopping it. Xen virtual guests are the most common example of resources that can be migrated in this manner. diff --git a/doc/sphinx/Pacemaker_Explained/resources.rst b/doc/sphinx/Pacemaker_Explained/resources.rst index 16d437f71a..b0ec74440e 100644 --- a/doc/sphinx/Pacemaker_Explained/resources.rst +++ b/doc/sphinx/Pacemaker_Explained/resources.rst @@ -1,832 +1,832 @@ .. _resource: Resources --------- .. _s-resource-primitive: .. index:: single: resource A *resource* is a service managed by Pacemaker. The simplest type of resource, a *primitive*, is described in this chapter. More complex forms, such as groups and clones, are described in later chapters. Every primitive has a *resource agent* that provides Pacemaker a standardized interface for managing the service. This allows Pacemaker to be agnostic about the services it manages. Pacemaker doesn't need to understand how the service works because it relies on the resource agent to do the right thing when asked. Every resource has a *standard* (also called *class*) specifying the interface that its resource agent follows, and a *type* identifying the specific service being managed. .. _s-resource-supported: .. index:: single: resource; standard Resource Standards ################## Pacemaker can use resource agents complying with these standards, described in more detail below: * ocf * lsb * systemd * service * stonith Support for some standards is controlled by build options and so might not be available in any particular build of Pacemaker. The command ``crm_resource --list-standards`` will show which standards are supported by the local build. .. index:: single: resource; OCF single: OCF; resources single: Open Cluster Framework; resources Open Cluster Framework ______________________ The Open Cluster Framework (OCF) Resource Agent API is a ClusterLabs standard for managing services. It is the most preferred since it is specifically designed for use in a Pacemaker cluster. OCF agents are scripts that support a variety of actions including ``start``, ``stop``, and ``monitor``. They may accept parameters, making them more flexible than other standards. The number and purpose of parameters is left to the agent, which advertises them via the ``meta-data`` action. Unlike other standards, OCF agents have a *provider* as well as a standard and type. For more information, see the "Resource Agents" chapter of *Pacemaker Administration* and the `OCF standard `_. .. _s-resource-supported-systemd: .. index:: single: Resource; Systemd single: Systemd; resources Systemd _______ Most Linux distributions use `Systemd `_ for system initialization and service management. *Unit files* specify how to manage services and are usually provided by the distribution. Pacemaker can manage systemd units of type service, socket, mount, timer, or path. Simply create a resource with ``systemd`` as the resource standard and the unit file name as the resource type. Do *not* run ``systemctl enable`` on the unit. .. important:: Make sure that any systemd services to be controlled by the cluster are *not* enabled to start at boot. .. index:: single: resource; LSB single: LSB; resources single: Linux Standard Base; resources Linux Standard Base ___________________ *LSB* resource agents, also known as `SysV-style `_, are scripts that provide start, stop, and status actions for a service. They are provided by some operating system distributions. If a full path is not given, they are assumed to be located in a directory specified when your Pacemaker software was built (usually ``/etc/init.d``). In order to be used with Pacemaker, they must conform to the `LSB specification `_ as it relates to init scripts. .. warning:: Some LSB scripts do not fully comply with the standard. For details on how to check whether your script is LSB-compatible, see the "Resource Agents" chapter of `Pacemaker Administration`. Common problems include: * Not implementing the ``status`` action * Not observing the correct exit status codes * Starting a started resource returns an error * Stopping a stopped resource returns an error .. important:: Make sure the host is *not* configured to start any LSB services at boot that will be controlled by the cluster. .. index:: single: Resource; System Services single: System Service; resources System Services _______________ Since there is more than one type of system service (``systemd`` and ``lsb``), Pacemaker supports a special ``service`` alias which intelligently figures out which one applies to a given cluster node. This is particularly useful when the cluster contains a mix of ``systemd`` and ``lsb``. If the ``service`` standard is specified, Pacemaker will try to find the named service as an LSB init script, and if none exists, a systemd unit file. .. index:: single: Resource; STONITH single: STONITH; resources STONITH _______ The ``stonith`` standard is used for managing fencing devices, discussed later in :ref:`fencing`. .. _primitive-resource: Resource Properties ################### These values tell the cluster which resource agent to use for the resource, where to find that resource agent and what standards it conforms to. .. table:: **Properties of a Primitive Resource** - :widths: 1 4 + :widths: 25 75 +-------------+------------------------------------------------------------------+ | Field | Description | +=============+==================================================================+ | id | .. index:: | | | single: id; resource | | | single: resource; property, id | | | | | | Your name for the resource | +-------------+------------------------------------------------------------------+ | class | .. index:: | | | single: class; resource | | | single: resource; property, class | | | | | | The standard the resource agent conforms to. Allowed values: | | | ``lsb``, ``ocf``, ``service``, ``stonith``, and ``systemd`` | +-------------+------------------------------------------------------------------+ | description | .. index:: | | | single: description; resource | | | single: resource; property, description | | | | | | Arbitrary text for user's use (ignored by Pacemaker) | +-------------+------------------------------------------------------------------+ | type | .. index:: | | | single: type; resource | | | single: resource; property, type | | | | | | The name of the Resource Agent you wish to use. E.g. | | | ``IPaddr`` or ``Filesystem`` | +-------------+------------------------------------------------------------------+ | provider | .. index:: | | | single: provider; resource | | | single: resource; property, provider | | | | | | The OCF spec allows multiple vendors to supply the same resource | | | agent. To use the OCF resource agents supplied by the Heartbeat | | | project, you would specify ``heartbeat`` here. | +-------------+------------------------------------------------------------------+ The XML definition of a resource can be queried with the **crm_resource** tool. For example: .. code-block:: none # crm_resource --resource Email --query-xml might produce: .. topic:: A system resource definition .. code-block:: xml .. note:: One of the main drawbacks to system services (lsb and systemd) is that they do not allow parameters .. topic:: An OCF resource definition .. code-block:: xml .. _resource_options: Resource Options ################ Resources have two types of options: *meta-attributes* and *instance attributes*. Meta-attributes apply to any type of resource, while instance attributes are specific to each resource agent. Resource Meta-Attributes ________________________ Meta-attributes are used by the cluster to decide how a resource should behave and can be easily set using the ``--meta`` option of the **crm_resource** command. .. list-table:: **Meta-attributes of a Primitive Resource** :class: longtable - :widths: 2 2 3 5 + :widths: 20 15 20 45 :header-rows: 1 * - Name - Type - Default - Description * - .. _meta_priority: .. index:: single: priority; resource option single: resource; option, priority priority - :ref:`score ` - 0 - If not all resources can be active, the cluster will stop lower-priority resources in order to keep higher-priority ones active. * - .. _meta_critical: .. index:: single: critical; resource option single: resource; option, critical critical - :ref:`boolean ` - true - Use this value as the default for ``influence`` in all :ref:`colocation constraints ` involving this resource, as well as in the implicit colocation constraints created if this resource is in a :ref:`group `. For details, see :ref:`s-coloc-influence`. *(since 2.1.0)* * - .. _meta_target_role: .. index:: single: target-role; resource option single: resource; option, target-role target-role - :ref:`enumeration ` - Started - What state should the cluster attempt to keep this resource in? Allowed values: * ``Stopped:`` Force the resource to be stopped * ``Started:`` Allow the resource to be started (and in the case of :ref:`promotable ` clone resources, promoted if appropriate) * ``Unpromoted:`` Allow the resource to be started, but only in the unpromoted role if the resource is :ref:`promotable ` * ``Promoted:`` Equivalent to ``Started`` * - .. _meta_is_managed: .. _is_managed: .. index:: single: is-managed; resource option single: resource; option, is-managed is-managed - :ref:`boolean ` - true - If false, the cluster will not start, stop, promote, or demote the resource on any node. Recurring actions for the resource are unaffected. Maintenance mode overrides this setting. * - .. _meta_maintenance: .. _rsc_maintenance: .. index:: single: maintenance; resource option single: resource; option, maintenance maintenance - :ref:`boolean ` - false - If true, the cluster will not start, stop, promote, or demote the resource on any node, and will pause any recurring monitors (except those specifying ``role`` as ``Stopped``). If true, the :ref:`maintenance-mode ` cluster option or :ref:`maintenance ` node attribute overrides this. * - .. _meta_resource_stickiness: .. _resource-stickiness: .. index:: single: resource-stickiness; resource option single: resource; option, resource-stickiness resource-stickiness - :ref:`score ` - 1 for individual clone instances, 0 for all other resources - A score that will be added to the current node when a resource is already active. This allows running resources to stay where they are, even if they would be placed elsewhere if they were being started from a stopped state. * - .. _meta_requires: .. _requires: .. index:: single: requires; resource option single: resource; option, requires requires - :ref:`enumeration ` - ``quorum`` for resources with a ``class`` of ``stonith``, otherwise ``unfencing`` if unfencing is active in the cluster, otherwise ``fencing`` if ``stonith-enabled`` is true, otherwise ``quorum`` - Conditions under which the resource can be started. Allowed values: * ``nothing:`` The cluster can always start this resource. * ``quorum:`` The cluster can start this resource only if a majority of the configured nodes are active. * ``fencing:`` The cluster can start this resource only if a majority of the configured nodes are active *and* any failed or unknown nodes have been :ref:`fenced `. * ``unfencing:`` The cluster can only start this resource if a majority of the configured nodes are active *and* any failed or unknown nodes have been fenced *and* only on nodes that have been :ref:`unfenced `. * - .. _meta_migration_threshold: .. index:: single: migration-threshold; resource option single: resource; option, migration-threshold migration-threshold - :ref:`score ` - INFINITY - How many failures may occur for this resource on a node, before this node is marked ineligible to host this resource. A value of 0 indicates that this feature is disabled (the node will never be marked ineligible); by contrast, the cluster treats ``INFINITY`` (the default) as a very large but finite number. This option has an effect only if the failed operation specifies ``on-fail`` as ``restart`` (the default), and additionally for failed ``start`` operations, if the cluster property ``start-failure-is-fatal`` is ``false``. * - .. _meta_failure_timeout: .. index:: single: failure-timeout; resource option single: resource; option, failure-timeout failure-timeout - :ref:`duration ` - 0 - Ignore previously failed resource actions after this much time has passed without new failures (potentially allowing the resource back to the node on which it failed, if it previously reached its ``migration-threshold`` there). A value of 0 indicates that failures do not expire. **WARNING:** If this value is low, and pending cluster activity prevents the cluster from responding to a failure within that time, then the failure will be ignored completely and will not cause recovery of the resource, even if a recurring action continues to report failure. It should be at least greater than the longest :ref:`action timeout ` for all resources in the cluster. A value in hours or days is reasonable. * - .. _meta_multiple_active: .. index:: single: multiple-active; resource option single: resource; option, multiple-active multiple-active - :ref:`enumeration ` - stop_start - What should the cluster do if it ever finds the resource active on more than one node? Allowed values: * ``block``: mark the resource as unmanaged * ``stop_only``: stop all active instances and leave them that way * ``stop_start``: stop all active instances and start the resource in one location only * ``stop_unexpected``: stop all active instances except where the resource should be active (this should be used only when extra instances are not expected to disrupt existing instances, and the resource agent's monitor of an existing instance is capable of detecting any problems that could be caused; note that any resources ordered after this will still need to be restarted) *(since 2.1.3)* * - .. _meta_allow_migrate: .. index:: single: allow-migrate; resource option single: resource; option, allow-migrate allow-migrate - :ref:`boolean ` - true for ``ocf:pacemaker:remote`` resources, false otherwise - Whether the cluster should try to "live migrate" this resource when it needs to be moved (see :ref:`live-migration`) * - .. _meta_allow_unhealthy_nodes: .. index:: single: allow-unhealthy-nodes; resource option single: resource; option, allow-unhealthy-nodes allow-unhealthy-nodes - :ref:`boolean ` - false - Whether the resource should be able to run on a node even if the node's health score would otherwise prevent it (see :ref:`node-health`) *(since 2.1.3)* * - .. _meta_container_attribute_target: .. index:: single: container-attribute-target; resource option single: resource; option, container-attribute-target container-attribute-target - :ref:`enumeration ` - - Specific to bundle resources; see :ref:`s-bundle-attributes` As an example of setting resource options, if you performed the following commands on an LSB Email resource: .. code-block:: none # crm_resource --meta --resource Email --set-parameter priority --parameter-value 100 # crm_resource -m -r Email -p multiple-active -v block the resulting resource definition might be: .. topic:: An LSB resource with cluster options .. code-block:: xml In addition to the cluster-defined meta-attributes described above, you may also configure arbitrary meta-attributes of your own choosing. Most commonly, this would be done for use in :ref:`rules `. For example, an IT department might define a custom meta-attribute to indicate which company department each resource is intended for. To reduce the chance of name collisions with cluster-defined meta-attributes added in the future, it is recommended to use a unique, organization-specific prefix for such attributes. .. _s-resource-defaults: Setting Global Defaults for Resource Meta-Attributes ____________________________________________________ To set a default value for a resource option, add it to the ``rsc_defaults`` section with ``crm_attribute``. For example, .. code-block:: none # crm_attribute --type rsc_defaults --name is-managed --update false would prevent the cluster from starting or stopping any of the resources in the configuration (unless of course the individual resources were specifically enabled by having their ``is-managed`` set to ``true``). Resource Instance Attributes ____________________________ The resource agents of some resource standards (lsb and systemd *not* among them) can be given parameters which determine how they behave and which instance of a service they control. If your resource agent supports parameters, you can add them with the ``crm_resource`` command. For example, .. code-block:: none # crm_resource --resource Public-IP --set-parameter ip --parameter-value 192.0.2.2 would create an entry in the resource like this: .. topic:: An example OCF resource with instance attributes .. code-block:: xml For an OCF resource, the result would be an environment variable called ``OCF_RESKEY_ip`` with a value of ``192.0.2.2``. The list of instance attributes supported by an OCF resource agent can be found by calling the resource agent with the ``meta-data`` command. The output contains an XML description of all the supported attributes, their purpose and default values. .. topic:: Displaying the metadata for the Dummy resource agent template .. code-block:: none # export OCF_ROOT=/usr/lib/ocf # $OCF_ROOT/resource.d/pacemaker/Dummy meta-data .. code-block:: xml 1.1 This is a dummy OCF resource agent. It does absolutely nothing except keep track of whether it is running or not, and can be configured so that actions fail or take a long time. Its purpose is primarily for testing, and to serve as a template for resource agent writers. Example stateless resource agent Location to store the resource state in. State file Fake password field Password Fake attribute that can be changed to cause a reload Fake attribute that can be changed to cause a reload Number of seconds to sleep during operations. This can be used to test how the cluster reacts to operation timeouts. Operation sleep duration in seconds. Start, migrate_from, and reload-agent actions will return failure if running on the host specified here, but the resource will run successfully anyway (future monitor calls will find it running). This can be used to test on-fail=ignore. Report bogus start failure on specified host If this is set, the environment will be dumped to this file for every call. Environment dump file Pacemaker Remote Resources ########################## :ref:`Pacemaker Remote ` nodes are defined by resources. .. _remote_nodes: .. index:: single: node; remote single: Pacemaker Remote; remote node single: remote node Remote nodes ____________ A remote node is defined by a connection resource using the special, built-in **ocf:pacemaker:remote** resource agent. .. list-table:: **ocf:pacemaker:remote Instance Attributes** :class: longtable - :widths: 2 2 3 5 + :widths: 25 10 15 50 :header-rows: 1 * - Name - Type - Default - Description * - .. _remote_server: .. index:: pair: remote node; server server - :ref:`text ` - resource ID - Hostname or IP address used to connect to the remote node. The remote executor on the remote node must be configured to accept connections on this address. * - .. _remote_port: .. index:: pair: remote node; port port - :ref:`port ` - 3121 - TCP port on the remote node used for its Pacemaker Remote connection. The remote executor on the remote node must be configured to listen on this port. * - .. _remote_reconnect_interval: .. index:: pair: remote node; reconnect_interval reconnect_interval - :ref:`duration ` - 0 - If positive, the cluster will attempt to reconnect to a remote node at this interval after an active connection has been lost. Otherwise, the cluster will attempt to reconnect immediately (after any fencing, if needed). .. _guest_nodes: .. index:: single: node; guest single: Pacemaker Remote; guest node single: guest node Guest Nodes ___________ When configuring a virtual machine as a guest node, the virtual machine is created using one of the usual resource agents for that purpose (for example, **ocf:heartbeat:VirtualDomain** or **ocf:heartbeat:Xen**), with additional meta-attributes. No restrictions are enforced on what agents may be used to create a guest node, but obviously the agent must create a distinct environment capable of running the remote executor and cluster resources. An additional requirement is that fencing the node hosting the guest node resource must be sufficient for ensuring the guest node is stopped. This means that not all hypervisors supported by **VirtualDomain** may be used to create guest nodes; if the guest can survive the hypervisor being fenced, it is unsuitable for use as a guest node. .. list-table:: **Guest node meta-attributes** :class: longtable - :widths: 2 2 3 5 + :widths: 25 10 20 45 :header-rows: 1 * - Name - Type - Default - Description * - .. _meta_remote_node: .. index:: single: remote-node; resource option single: resource; option, remote-node remote-node - :ref:`text ` - - If specified, this resource defines a guest node using this node name. The guest must be configured to run the remote executor when it is started. This value *must not* be the same as any resource or node ID. * - .. _meta_remote_addr: .. index:: single: remote-addr; resource option single: resource; option, remote-addr remote-addr - :ref:`text ` - value of ``remote-node`` - If ``remote-node`` is specified, the hostname or IP address used to connect to the guest. The remote executor on the guest must be configured to accept connections on this address. * - .. _meta_remote_port: .. index:: single: remote-port; resource option single: resource; option, remote-port remote-port - :ref:`port ` - 3121 - If ``remote-node`` is specified, the port on the guest used for its Pacemaker Remote connection. The remote executor on the guest must be configured to listen on this port. * - .. _meta_remote_connect_timeout: .. index:: single: remote-connect-timeout; resource option single: resource; option, remote-connect-timeout remote-connect-timeout - :ref:`timeout ` - 60s - If ``remote-node`` is specified, how long before a pending guest connection will time out. * - .. _meta_remote_allow_migrate: .. index:: single: remote-allow-migrate; resource option single: resource; option, remote-allow-migrate remote-allow-migrate - :ref:`boolean ` - true - If ``remote-node`` is specified, this acts as the ``allow-migrate`` meta-attribute for its implicitly created remote connection resource (``ocf:pacemaker:remote``). Removing Pacemaker Remote Nodes _______________________________ If the resource creating a remote node connection or guest node is removed from the configuration, status output may continue to show the affected node (as offline). If you want to get rid of that output, run the following command, replacing ``$NODE_NAME`` appropriately: .. code-block:: none # crm_node --force --remove $NODE_NAME .. WARNING:: Be absolutely sure that there are no references to the node's resource in the configuration before running the above command. diff --git a/doc/sphinx/Pacemaker_Explained/rules.rst b/doc/sphinx/Pacemaker_Explained/rules.rst index 13134daafa..ff8185c90a 100644 --- a/doc/sphinx/Pacemaker_Explained/rules.rst +++ b/doc/sphinx/Pacemaker_Explained/rules.rst @@ -1,1218 +1,1218 @@ .. index:: single: rule .. _rules: Rules ----- Rules make a configuration more dynamic, allowing values to depend on conditions such as time of day or the value of a node attribute. For example, rules can: * Set a higher value for :ref:`resource-stickiness ` during working hours to minimize downtime, and a lower value on weekends to allow resources to move to their most preferred locations when people aren't around * Automatically place the cluster into maintenance mode during a scheduled maintenance window * Restrict a particular department's resources to run on certain nodes, as determined by custom resource meta-attributes and node attributes .. index:: pair: rule; XML element pair: rule; options Rule Options ############ Each context that supports rules may contain a single ``rule`` element. .. list-table:: **Attributes of a rule Element** :class: longtable - :widths: 2 2 2 5 + :widths: 15 15 10 60 :header-rows: 1 * - Name - Type - Default - Description * - .. _rule_id: .. index:: pair: rule; id id - :ref:`id ` - - A unique name for this element (required) * - .. _boolean_op: .. index:: pair: rule; boolean-op boolean-op - :ref:`enumeration ` - ``and`` - How to combine conditions if this rule contains more than one. Allowed values: * ``and``: the rule is satisfied only if all conditions are satisfied * ``or``: the rule is satisfied if any condition is satisfied .. _rule_conditions: .. index:: single: rule; conditions single: rule; contexts Rule Conditions and Contexts ############################ A ``rule`` element must contain one or more conditions. A condition is any of the following, which will be described in more detail later: * a :ref:`date/time expression ` * a :ref:`node attribute expression ` * a :ref:`resource type expression ` * an :ref:`operation type expression ` * another ``rule`` (allowing for complex combinations of conditions) Each type of condition is allowed only in certain contexts. Although any given context may contain only one ``rule`` element, that element may contain any number of conditions, including other ``rule`` elements. Rules may be used in the following contexts, which also will be described in more detail later: * a :ref:`location constraint ` * a :ref:`cluster_property_set ` element (within the ``crm_config`` element) * an :ref:`instance_attributes ` element (within an ``alert``, ``bundle``, ``clone``, ``group``, ``node``, ``op``, ``primitive``, ``recipient``, or ``template`` element) * a :ref:`meta_attributes ` element (within an ``alert``, ``bundle``, ``clone``, ``group``, ``op``, ``op_defaults``, ``primitive``, ``recipient``, ``rsc_defaults``, or ``template`` element) * a :ref:`utilization ` element (within a ``node``, ``primitive``, or ``template`` element) .. _date_expression: .. index:: single: rule; date/time expression pair: XML element; date_expression Date/Time Expressions ##################### The ``date_expression`` element configures a rule condition based on the current date and time. It is allowed in rules in any context. It may contain a ``date_spec`` or ``duration`` element depending on the ``operation`` as described below. .. list-table:: **Attributes of a date_expression Element** :class: longtable - :widths: 1 1 1 4 + :widths: 15 15 20 50 :header-rows: 1 * - Name - Type - Default - Description * - .. _date_expression_id: .. index:: pair: date_expression; id id - :ref:`id ` - - A unique name for this element (required) * - .. _date_expression_start: .. index:: pair: date_expression; start start - :ref:`ISO 8601 ` - - The beginning of the desired time range. Meaningful with an ``operation`` of ``in_range`` or ``gt``. * - .. _date_expression_end: .. index:: pair: date_expression; end end - :ref:`ISO 8601 ` - - The end of the desired time range. Meaningful with an ``operation`` of ``in_range`` or ``lt``. * - .. _date_expression_operation: .. index:: pair: date_expression; operation operation - :ref:`enumeration ` - ``in_range`` - Specifies how to compare the current date/time against a desired time range. Allowed values: * ``gt:`` The expression is satisfied if the current date/time is after ``start`` (which is required) * ``lt:`` The expression is satisfied if the current date/time is before ``end`` (which is required) * ``in_range:`` The expression is satisfied if the current date/time is greater than or equal to ``start`` (if specified) and less than or equal to either ``end`` (if specified) or ``start`` plus the value of the :ref:`duration ` element (if one is contained in the ``date_expression``). At least one of ``start`` or ``end`` must be specified. If both ``end`` and ``duration`` are specified, ``duration`` is ignored. * ``date_spec:`` The expression is satisfied if the current date/time matches the specification given in the contained :ref:`date_spec ` element (which is required) .. _date_spec: .. index:: single: date specification pair: XML element; date_spec Date Specifications ___________________ A ``date_spec`` element is used within a ``date_expression`` to specify a combination of dates and times that satisfy the expression. .. list-table:: **Attributes of a date_spec Element** :class: longtable - :widths: 1 1 1 4 + :widths: 15 15 10 60 :header-rows: 1 * - Name - Type - Default - Description * - .. _date_spec_id: .. index:: pair: date_spec; id id - :ref:`id ` - - A unique name for this element (required) * - .. _date_spec_seconds: .. index:: pair: date_spec; seconds seconds - :ref:`range ` - - If this is set, the expression is satisfied only if the current time's second is within this range. Allowed integers: 0 to 59. * - .. _date_spec_minutes: .. index:: pair: date_spec; minutes minutes - :ref:`range ` - - If this is set, the expression is satisfied only if the current time's minute is within this range. Allowed integers: 0 to 59. * - .. _date_spec_hours: .. index:: pair: date_spec; hours hours - :ref:`range ` - - If this is set, the expression is satisfied only if the current time's hour is within this range. Allowed integers: 0 to 23 where 0 is midnight and 23 is 11 p.m. * - .. _date_spec_monthdays: .. index:: pair: date_spec; monthdays monthdays - :ref:`range ` - - If this is set, the expression is satisfied only if the current date's day of the month is in this range. Allowed integers: 1 to 31. * - .. _date_spec_weekdays: .. index:: pair: date_spec; weekdays weekdays - :ref:`range ` - - If this is set, the expression is satisfied only if the current date's ordinal day of the week is in this range. Allowed integers: 1-7 (where 1 is Monday and 7 is Sunday). * - .. _date_spec_yeardays: .. index:: pair: date_spec; yeardays yeardays - :ref:`range ` - - If this is set, the expression is satisfied only if the current date's ordinal day of the year is in this range. Allowed integers: 1-366. * - .. _date_spec_months: .. index:: pair: date_spec; months months - :ref:`range ` - - If this is set, the expression is satisfied only if the current date's month is in this range. Allowed integers: 1-12 where 1 is January and 12 is December. * - .. _date_spec_weeks: .. index:: pair: date_spec; weeks weeks - :ref:`range ` - - If this is set, the expression is satisfied only if the current date's ordinal week of the year is in this range. Allowed integers: 1-53. * - .. _date_spec_years: .. index:: pair: date_spec; years years - :ref:`range ` - - If this is set, the expression is satisfied only if the current date's year according to the Gregorian calendar is in this range. * - .. _date_spec_weekyears: .. index:: pair: date_spec; weekyears weekyears - :ref:`range ` - - If this is set, the expression is satisfied only if the current date's year in which the week started (according to the ISO 8601 standard) is in this range. * - .. _date_spec_moon: .. index:: pair: date_spec; moon moon - :ref:`range ` - - If this is set, the expression is satisfied only if the current date's phase of the moon is in this range. Allowed values are 0 to 7 where 0 is the new moon and 4 is the full moon. *(deprecated since 2.1.6)* .. note:: Pacemaker can calculate when evaluation of a ``date_expression`` with an ``operation`` of ``gt``, ``lt``, or ``in_range`` will next change, and schedule a cluster re-check for that time. However, it does not do this for ``date_spec``. Instead, it evaluates the ``date_spec`` whenever a cluster re-check naturally happens via a cluster event or the ``cluster-recheck-interval`` cluster option. For example, if you have a ``date_spec`` enabling a resource from 9 a.m. to 5 p.m., and ``cluster-recheck-interval`` has been set to 5 minutes, then sometime between 9 a.m. and 9:05 a.m. the cluster would notice that it needs to start the resource, and sometime between 5 p.m. and 5:05 p.m. it would realize that it needs to stop the resource. The timing of the actual start and stop actions will further depend on factors such as any other actions the cluster may need to perform first, and the load of the machine. .. _duration_element: .. index:: single: duration pair: XML element; duration Durations _________ A ``duration`` element is used within a ``date_expression`` to calculate an ending value for ``in_range`` operations when ``end`` is not supplied. .. list-table:: **Attributes of a duration Element** :class: longtable - :widths: 1 1 1 4 + :widths: 15 15 10 60 :header-rows: 1 * - Name - Type - Default - Description * - .. _duration_id: .. index:: pair: duration; id id - :ref:`id ` - - A unique name for this element (required) * - .. _duration_seconds: .. index:: pair: duration; seconds seconds - :ref:`integer ` - 0 - Number of seconds to add to the total duration * - .. _duration_minutes: .. index:: pair: duration; minutes minutes - :ref:`integer ` - 0 - Number of minutes to add to the total duration * - .. _duration_hours: .. index:: pair: duration; hours hours - :ref:`integer ` - 0 - Number of hours to add to the total duration * - .. _duration_days: .. index:: pair: duration; days days - :ref:`integer ` - 0 - Number of days to add to the total duration * - .. _duration_weeks: .. index:: pair: duration; weeks weeks - :ref:`integer ` - 0 - Number of weeks to add to the total duration * - .. _duration_months: .. index:: pair: duration; months months - :ref:`integer ` - 0 - Number of months to add to the total duration * - .. _duration_years: .. index:: pair: duration; years years - :ref:`integer ` - 0 - Number of years to add to the total duration Example Date/Time Expressions _____________________________ .. topic:: Satisfied if the current year is 2005 .. code-block:: xml or equivalently: .. code-block:: xml .. topic:: 9 a.m. to 5 p.m. Monday through Friday .. code-block:: xml Note that the ``16`` matches all the way through ``16:59:59``, because the numeric value of the hour still matches. .. topic:: 9 a.m. to 6 p.m. Monday through Friday, or anytime Saturday .. code-block:: xml .. topic:: 9 a.m. to 5 p.m. or 9 p.m. to 12 a.m. Monday through Friday .. code-block:: xml .. topic:: Mondays in March 2005 .. code-block:: xml .. note:: Because no time is specified with the above dates, 00:00:00 is implied. This means that the range includes all of 2005-03-01 but only the first second of 2005-04-01. You may wish to write ``end`` as ``"2005-03-31T23:59:59"`` to avoid confusion. .. index:: single: rule; node attribute expression single: node attribute; rule expression pair: XML element; expression .. _node_attribute_expressions: Node Attribute Expressions ########################## The ``expression`` element configures a rule condition based on the value of a node attribute. It is allowed in rules in location constraints and in ``instance_attributes`` elements within ``bundle``, ``clone``, ``group``, ``op``, ``primitive``, and ``template`` elements. .. list-table:: **Attributes of an expression Element** :class: longtable - :widths: 1 1 3 5 + :widths: 15 15 30 40 :header-rows: 1 * - Name - Type - Default - Description * - .. _expression_id: .. index:: pair: expression; id id - :ref:`id ` - - A unique name for this element (required) * - .. _expression_attribute: .. index:: pair: expression; attribute attribute - :ref:`text ` - - Name of the node attribute to test (required) * - .. _expression_operation: .. index:: pair: expression; operation operation - :ref:`enumeration ` - - The comparison to perform (required). Allowed values: * ``defined:`` The expression is satisfied if the node has the named attribute * ``not_defined:`` The expression is satisfied if the node does not have the named attribute * ``lt:`` The expression is satisfied if the node attribute value is less than the reference value * ``gt:`` The expression is satisfied if the node attribute value is greater than the reference value * ``lte:`` The expression is satisfied if the node attribute value is less than or equal to the reference value * ``gte:`` The expression is satisfied if the node attribute value is greater than or equal to the reference value * ``eq:`` The expression is satisfied if the node attribute value is equal to the reference value * ``ne:`` The expression is satisfied if the node attribute value is not equal to the reference value * - .. _expression_type: .. index:: pair: expression; type type - :ref:`enumeration ` - The default type for ``lt``, ``gt``, ``lte``, and ``gte`` operations is ``number`` if either value contains a decimal point character, or ``integer`` otherwise. The default type for all other operations is ``string``. If a numeric parse fails for either value, then the values are compared as type ``string``. - How to interpret values. Allowed values are ``string``, ``integer`` *(since 2.0.5)*, ``number``, and ``version``. ``integer`` truncates floating-point values if necessary before performing a 64-bit integer comparison. ``number`` performs a double-precision floating-point comparison *(32-bit integer before 2.0.5)*. * - .. _expression_value: .. index:: pair: expression; value value - :ref:`text ` - - Reference value to compare node attribute against (used only with, and required for, operations other than ``defined`` and ``not_defined``) * - .. _expression_value_source: .. index:: pair: expression; value-source value-source - :ref:`enumeration ` - ``literal`` - How the reference value is obtained. Allowed values: * ``literal``: ``value`` contains the literal reference value to compare * ``param``: ``value`` contains the name of a resource parameter to compare (valid only in the context of a location constraint) * ``meta``: ``value`` is the name of a resource meta-attribute to compare (valid only in the context of a location constraint) .. _node-attribute-expressions-special: In addition to custom node attributes defined by the administrator, the cluster defines special, built-in node attributes for each node that can also be used in rule expressions. .. list-table:: **Built-in Node Attributes** :class: longtable - :widths: 1 4 + :widths: 25 75 :header-rows: 1 * - Name - Description * - #uname - :ref:`Node name ` * - #id - Node ID * - #kind - Node type (``cluster`` for cluster nodes, ``remote`` for Pacemaker Remote nodes created with the ``ocf:pacemaker:remote`` resource, and ``container`` for Pacemaker Remote guest nodes and bundle nodes) * - #is_dc - ``true`` if this node is the cluster's Designated Controller (DC), ``false`` otherwise * - #cluster-name - The value of the ``cluster-name`` cluster property, if set * - #site-name - The value of the ``site-name`` node attribute, if set, otherwise identical to ``#cluster-name`` .. _rsc_expression: .. index:: single: rule; resource expression single: resource; rule expression pair: XML element; rsc_expression Resource Type Expressions ######################### The ``rsc_expression`` element *(since 2.0.5)* configures a rule condition based on the agent used for a resource. It is allowed in rules in a ``meta_attributes`` element within a ``rsc_defaults`` or ``op_defaults`` element. .. list-table:: **Attributes of a rsc_expression Element** :class: longtable - :widths: 1 1 1 4 + :widths: 15 15 10 60 :header-rows: 1 * - Name - Type - Default - Description * - .. _rsc_expression_id: .. index:: pair: rsc_expression; id id - :ref:`id ` - - A unique name for this element (required) * - .. _rsc_expression_class: .. index:: pair: rsc_expression; class class - :ref:`text ` - - If this is set, the expression is satisfied only if the resource's agent standard matches this value * - .. _rsc_expression_provider: .. index:: pair: rsc_expression; provider provider - :ref:`text ` - - If this is set, the expression is satisfied only if the resource's agent provider matches this value * - .. _rsc_expression_type: .. index:: pair: rsc_expression; type type - :ref:`text ` - - If this is set, the expression is satisfied only if the resource's agent type matches this value Example Resource Type Expressions _________________________________ .. topic:: Satisfied for ``ocf:heartbeat:IPaddr2`` resources .. code-block:: xml .. topic:: Satisfied for ``stonith:fence_xvm`` resources .. code-block:: xml .. _op_expression: .. index:: single: rule; operation expression single: operation; rule expression pair: XML element; op_expression Operation Type Expressions ########################## The ``op_expression`` element *(since 2.0.5)* configures a rule condition based on a resource operation name and interval. It is allowed in rules in a ``meta_attributes`` element within an ``op_defaults`` element. .. list-table:: **Attributes of an op_expression Element** :class: longtable - :widths: 1 1 1 4 + :widths: 15 15 10 60 :header-rows: 1 * - Name - Type - Default - Description * - .. _op_expression_id: .. index:: pair: op_expression; id id - :ref:`id ` - - A unique name for this element (required) * - .. _op_expression_name: .. index:: pair: op_expression; name name - :ref:`text ` - - The expression is satisfied only if the operation's name matches this value (required) * - .. _op_expression_interval: .. index:: pair: op_expression; interval interval - :ref:`duration ` - - If this is set, the expression is satisfied only if the operation's interval matches this value Example Operation Type Expressions __________________________________ .. topic:: Expression is satisfied for all monitor actions .. code-block:: xml .. topic:: Expression is satisfied for all monitor actions with a 10-second interval .. code-block:: xml .. _location_rule: .. index:: pair: location constraint; rule Using Rules to Determine Resource Location ########################################## If a :ref:`location constraint ` contains a rule, the cluster will apply the constraint to all nodes where the rule is satisfied. This acts as if identical location constraints without rules were defined for each of the nodes. In the context of a location constraint, ``rule`` elements may take additional attributes. These have an effect only when set for the constraint's top-level ``rule``; they are ignored if set on a subrule. .. list-table:: **Extra Attributes of a rule Element in a Location Constraint** :class: longtable - :widths: 2 2 1 5 + :widths: 20 15 10 55 :header-rows: 1 * - Name - Type - Default - Description * - .. _rule_role: .. index:: pair: rule; role role - :ref:`enumeration ` - ``Started`` - If this is set in the constraint's top-level rule, the constraint acts as if ``role`` were set to this in the ``rsc_location`` element. * - .. _rule_score: .. index:: pair: rule; score score - :ref:`score ` - - If this is set in the constraint's top-level rule, the constraint acts as if ``score`` were set to this in the ``rsc_location`` element. Only one of ``score`` and ``score-attribute`` may be set. * - .. _rule_score_attribute: .. index:: pair: rule; score-attribute score-attribute - :ref:`text ` - - If this is set in the constraint's top-level rule, the constraint acts as if ``score`` were set to the value of this node attribute on each node where the rule is satisfied. Only one of ``score`` and ``score-attribute`` may be set. Consider the following simple location constraint: .. topic:: Prevent resource ``webserver`` from running on node ``node3`` .. code-block:: xml The same constraint can be written more verbosely using a rule: .. topic:: Prevent resource ``webserver`` from running on node ``node3`` using a rule .. code-block:: xml The advantage of using the expanded form is that one could add more expressions (for example, limiting the constraint to certain days of the week). Location Rules Based on Other Node Properties _____________________________________________ The expanded form allows us to match node attributes other than its name. As an example, consider this configuration of custom node attributes specifying each node's CPU capacity: .. topic:: Sample node section with node attributes .. code-block:: xml We can use a rule to prevent a resource from running on underpowered machines: .. topic:: Rule using a node attribute (to be used inside a location constraint) .. code-block:: xml Using ``score-attribute`` Instead of ``score`` ______________________________________________ When using ``score-attribute`` instead of ``score``, each node matched by the rule has its score adjusted according to its value for the named node attribute. In the previous example, if the location constraint rule used ``score-attribute="cpu_mips"`` instead of ``score="-INFINITY"``, node ``c001n01`` would have its preference to run the resource increased by 1234 whereas node ``c001n02`` would have its preference increased by 5678. .. _s-rsc-pattern-rules: Specifying location scores using pattern submatches ___________________________________________________ Location constraints may use :ref:`rsc-pattern ` to apply the constraint to all resources whose IDs match the given pattern. The pattern may contain up to 9 submatches in parentheses, whose values may be used as ``%1`` through ``%9`` in a ``rule`` element's ``score-attribute`` or an ``expression`` element's ``attribute``. For example, the following configuration excerpt gives the resources **server-httpd** and **ip-httpd** a preference of 100 on node1 and 50 on node2, and **ip-gateway** a preference of -100 on node1 and 200 on node2. .. topic:: Location constraint using submatches .. code-block:: xml .. _option_rule: .. index:: pair: cluster option; rule pair: instance attribute; rule pair: meta-attribute; rule pair: resource defaults; rule pair: operation defaults; rule pair: node attribute; rule Using Rules to Define Options ############################# Rules may be used to control a variety of options: * :ref:`Cluster options ` (as ``cluster_property_set`` elements) * :ref:`Node attributes ` (as ``instance_attributes`` or ``utilization`` elements inside a ``node`` element) * :ref:`Resource options ` (as ``utilization``, ``meta_attributes``, or ``instance_attributes`` elements inside a resource definition element or ``op`` , ``rsc_defaults``, ``op_defaults``, or ``template`` element) * :ref:`Operation options ` (as ``meta_attributes`` elements inside an ``op`` or ``op_defaults`` element) * :ref:`Alert options ` (as ``instance_attributes`` or ``meta_attributes`` elements inside an ``alert`` or ``recipient`` element) Using Rules to Control Resource Options _______________________________________ Often some cluster nodes will be different from their peers. Sometimes, these differences (for example, the location of a binary, or the names of network interfaces) require resources to be configured differently depending on the machine they're hosted on. By defining multiple ``instance_attributes`` elements for the resource and adding a rule to each, we can easily handle these special cases. In the example below, ``mySpecialRsc`` will use eth1 and port 9999 when run on node1, eth2 and port 8888 on node2 and default to eth0 and port 9999 for all other nodes. .. topic:: Defining different resource options based on the node name .. code-block:: xml Multiple ``instance_attributes`` elements are evaluated from highest score to lowest. If not supplied, the score defaults to zero. Objects with equal scores are processed in their listed order. If an ``instance_attributes`` object has no rule or a satisfied ``rule``, then for any parameter the resource does not yet have a value for, the resource will use the value defined by the ``instance_attributes``. For example, given the configuration above, if the resource is placed on ``node1``: * ``special-node1`` has the highest score (3) and so is evaluated first; its rule is satisfied, so ``interface`` is set to ``eth1``. * ``special-node2`` is evaluated next with score 2, but its rule is not satisfied, so it is ignored. * ``defaults`` is evaluated last with score 1, and has no rule, so its values are examined; ``interface`` is already defined, so the value here is not used, but ``port`` is not yet defined, so ``port`` is set to ``9999``. Using Rules to Control Resource Defaults ________________________________________ Rules can be used for resource and operation defaults. The following example illustrates how to set a different ``resource-stickiness`` value during and outside work hours. This allows resources to automatically move back to their most preferred hosts, but at a time that (in theory) does not interfere with business activities. .. topic:: Change ``resource-stickiness`` during working hours .. code-block:: xml ``rsc_expression`` is valid within both ``rsc_defaults`` and ``op_defaults``; ``op_expression`` is valid only within ``op_defaults``. .. topic:: Default all IPaddr2 resources to stopped .. code-block:: xml .. topic:: Default all monitor action timeouts to 7 seconds .. code-block:: xml .. topic:: Default the timeout on all 10-second-interval monitor actions on ``IPaddr2`` resources to 8 seconds .. code-block:: xml .. index:: pair: rule; cluster option Using Rules to Control Cluster Options ______________________________________ Controlling cluster options is achieved in much the same manner as specifying different resource options on different nodes. The following example illustrates how to set ``maintenance_mode`` during a scheduled maintenance window. This will keep the cluster running but not monitor, start, or stop resources during this time. .. topic:: Schedule a maintenance window for 9 to 11 p.m. CDT Sept. 20, 2019 .. code-block:: xml .. important:: The ``cluster_property_set`` with an ``id`` set to "cib-bootstrap-options" will *always* have the highest priority, regardless of any scores. Therefore, rules in another ``cluster_property_set`` can never take effect for any properties listed in the bootstrap set. diff --git a/doc/sphinx/Pacemaker_Explained/status.rst b/doc/sphinx/Pacemaker_Explained/status.rst index 2cdf20c7e8..f7668177f2 100644 --- a/doc/sphinx/Pacemaker_Explained/status.rst +++ b/doc/sphinx/Pacemaker_Explained/status.rst @@ -1,459 +1,459 @@ .. index:: pair: XML element; status Status ------ Pacemaker automatically generates a ``status`` section in the CIB (inside the ``cib`` element, at the same level as ``configuration``). The status is transient, and is not stored to disk with the rest of the CIB. The section's structure and contents are internal to Pacemaker and subject to change from release to release. Its often obscure element and attribute names are kept for historical reasons, to maintain compatibility with older versions during rolling upgrades. Users should not modify the section directly, though various command-line tool options affect it indirectly. .. index:: pair: XML element; node_state single: node; state Node State ########## The ``status`` element contains ``node_state`` elements for each node in the cluster (and potentially nodes that have been removed from the configuration since the cluster started). The ``node_state`` element has attributes that allow the cluster to determine whether the node is healthy. .. topic:: Example minimal node state entry .. code-block:: xml .. list-table:: **Attributes of a node_state Element** :class: longtable - :widths: 1 1 3 + :widths: 20 20 60 :header-rows: 1 * - Name - Type - Description * - .. _node_state_id: .. index:: pair: node_state; id id - :ref:`text ` - Node ID (identical to ``id`` of corresponding ``node`` element in the ``configuration`` section) * - .. node_state_uname: .. index:: pair: node_state; uname uname - :ref:`text ` - Node name (identical to ``uname`` of corresponding ``node`` element in the ``configuration`` section) * - .. node_state_in_ccm: .. index:: pair: node_state; in_ccm in_ccm - :ref:`epoch time ` *(since 2.1.7; previously boolean)* - If the node's controller is currently in the cluster layer's membership, this is the epoch time at which it joined (or 1 if the node is in the process of leaving the cluster), otherwise 0 *(since 2.1.7; previously, it was "true" or "false")* * - .. node_state_crmd: .. index:: pair: node_state; crmd crmd - :ref:`epoch time ` *(since 2.1.7; previously an enumeration)* - If the node's controller is currently in the cluster layer's controller messaging group, this is the epoch time at which it joined, otherwise 0 *(since 2.1.7; previously, the value was either "online" or "offline")* * - .. node_state_crm_debug_origin: .. index:: pair: node_state; crm-debug-origin crm-debug-origin - :ref:`text ` - Name of the source code function that recorded this ``node_state`` element (for debugging) * - .. node_state_join: .. index:: pair: node_state; join join - :ref:`enumeration ` - Current status of node's controller join sequence (and thus whether it is eligible to run resources). Allowed values: * ``down``: Not yet joined * ``pending``: In the process of joining or leaving * ``member``: Fully joined * ``banned``: Rejected by DC * - .. node_state_expected: .. index:: pair: node_state; expected expected - :ref:`enumeration ` - What cluster expects ``join`` to be in the immediate future. Allowed values are same as for ``join``. .. _transient_attributes: .. index:: pair: XML element; transient_attributes single: node; transient attribute single: node attribute; transient Transient Node Attributes ######################### The ``transient_attributes`` section specifies transient :ref:`node_attributes`. In addition to any values set by the administrator or resource agents using the ``attrd_updater`` or ``crm_attribute`` tools, the cluster stores various state information here. .. topic:: Example transient node attributes for a node .. code-block:: xml .. index:: pair: XML element; lrm pair: XML element; lrm_resources pair: node; history Node History ############ Each ``node_state`` element contains an ``lrm`` element with a history of certain resource actions performed on the node. The ``lrm`` element contains an ``lrm_resources`` element. .. index:: pair: XML element; lrm_resource pair: resource; history Resource History ________________ The ``lrm_resources`` element contains an ``lrm_resource`` element for each resource that has had an action performed on the node. An ``lrm_resource`` entry has attributes allowing the cluster to stop the resource safely even if it is removed from the configuration. Specifically, the resource's ``id``, ``class``, ``type`` and ``provider`` are recorded. .. index:: pair: XML element; lrm_rsc_op pair: action; history Action History ______________ Each ``lrm_resource`` element contains an ``lrm_rsc_op`` element for each recorded action performed for that resource on that node. (Not all actions are recorded, just enough to determine the resource's state.) .. list-table:: **Attributes of an lrm_rsc_op element** :class: longtable - :widths: 1 1 3 + :widths: 20 20 60 :header-rows: 1 * - Name - Type - Description * - .. _lrm_rsc_op_id: .. index:: pair: lrm_rsc_op; id id - :ref:`text ` - Identifier for the history entry constructed from the resource ID, action name or history entry type, and action interval. * - .. _lrm_rsc_op_operation_key: .. index:: pair: lrm_rsc_op; operation_key operation_key - :ref:`text ` - Identifier for the action that was executed, constructed from the resource ID, action name, and action interval. * - .. _lrm_rsc_op_operation: .. index:: pair: lrm_rsc_op; operation operation - :ref:`text ` - The name of the action the history entry is for * - .. _lrm_rsc_op_crm_debug_origin: .. index:: pair: lrm_rsc_op; crm-debug-origin crm-debug-origin - :ref:`text ` - Name of the source code function that recorded this entry (for debugging) * - .. _lrm_rsc_op_crm_feature_set: .. index:: pair: lrm_rsc_op; crm_feature_set crm_feature_set - :ref:`version ` - The Pacemaker feature set used to record this entry. * - .. _lrm_rsc_op_transition_key: .. index:: pair: lrm_rsc_op; transition-key transition-key - :ref:`text ` - A concatenation of the action's transition graph action number, the transition graph number, the action's expected result, and the UUID of the controller instance that scheduled it. * - .. _lrm_rsc_op_transition_magic: .. index:: pair: lrm_rsc_op; transition-magic transition-magic - :ref:`text ` - A concatenation of ``op-status``, ``rc-code``, and ``transition-key``. * - .. _lrm_rsc_op_exit_reason: .. index:: pair: lrm_rsc_op; exit-reason exit-reason - :ref:`text ` - An error message (if available) from the resource agent or Pacemaker if the action did not return success. * - .. _lrm_rsc_op_on_node: .. index:: pair: lrm_rsc_op; on_node on_node - :ref:`text ` - The name of the node that executed the action (identical to the ``uname`` of the enclosing ``node_state`` element) * - .. _lrm_rsc_op_call_id: .. index:: pair: lrm_rsc_op; call-id call-id - :ref:`integer ` - A node-specific counter used to determine the order in which actions were executed. * - .. _lrm_rsc_op_rc_code: .. index:: pair: lrm_rsc_op; rc-code rc-code - :ref:`integer ` - The resource agent's exit status for this action. Refer to the *Resource Agents* chapter of *Pacemaker Administration* for how these values are interpreted. * - .. _lrm_rsc_op_op_status: .. index:: pair: lrm_rsc_op; op-status op-status - :ref:`integer ` - The execution status of this action. The meanings of these codes are internal to Pacemaker. * - .. _lrm_rsc_op_interval: .. index:: pair: lrm_rsc_op; interval interval - :ref:`nonnegative integer ` - If the action is recurring, its frequency (in milliseconds), otherwise 0. * - .. _lrm_rsc_op_last_rc_change: .. index:: pair: lrm_rsc_op; last-rc-change last-rc-change - :ref:`epoch time ` - Node-local time at which the action first returned the current value of ``rc-code``. * - .. _lrm_rsc_op_exec_time: .. index:: pair: lrm_rsc_op; exec-time exec-time - :ref:`integer ` - Time (in seconds) that action execution took (if known) * - .. _lrm_rsc_op_queue_time: .. index:: pair: lrm_rsc_op; queue-time queue-time - :ref:`integer ` - Time (in seconds) that action was queued in the local executor (if known) * - .. _lrm_rsc_op_op_digest: .. index:: pair: lrm_rsc_op; op-digest op-digest - :ref:`text ` - If present, this is a hash of the parameters passed to the action. If a hash of the currently configured parameters does not match this, that means the resource configuration changed since the action was performed, and the resource must be reloaded or restarted. * - .. _lrm_rsc_op_op_restart_digest: .. index:: pair: lrm_rsc_op; op-restart-digest op-restart-digest - :ref:`text ` - If present, the resource agent supports reloadable parameters, and this is a hash of the non-reloadable parameters passed to the action. This allows the cluster to choose between reload and restart when one is needed. * - .. _lrm_rsc_op_op_secure_digest: .. index:: pair: lrm_rsc_op; op-secure-digest op-secure-digest - :ref:`text ` - If present, the resource agent marks some parameters as sensitive, and this is a hash of the non-sensitive parameters passed to the action. This allows the value of sensitive parameters to be removed from a saved copy of the CIB while still allowing scheduler simulations to be performed on that copy. Simple Operation History Example ________________________________ .. topic:: A monitor operation (determines current state of the ``apcstonith`` resource) .. code-block:: xml The above example shows the history entry for a probe (non-recurring monitor operation) for the ``apcstonith`` resource. The cluster schedules probes for every configured resource on a node when the node first starts, in order to determine the resource's current state before it takes any further action. From the ``transition-key``, we can see that this was the 22nd action of the 2nd graph produced by this instance of the controller (2668bbeb-06d5-40f9-936d-24cb7f87006a). The third field of the ``transition-key`` contains a 7, which indicates that the cluster expects to find the resource inactive. By looking at the ``rc-code`` property, we see that this was the case. As that is the only action recorded for this node, we can conclude that the cluster started the resource elsewhere. Complex Operation History Example _________________________________ .. topic:: Resource history of a ``pingd`` clone with multiple entries .. code-block:: xml When more than one history entry exists, it is important to first sort them by ``call-id`` before interpreting them. Once sorted, the above example can be summarized as: #. A non-recurring monitor operation returning 7 (not running), with a ``call-id`` of 3 #. A stop operation returning 0 (success), with a ``call-id`` of 32 #. A start operation returning 0 (success), with a ``call-id`` of 33 #. A recurring monitor returning 0 (success), with a ``call-id`` of 34 The cluster processes each history entry to build up a picture of the resource's state. After the first and second entries, it is considered stopped, and after the third it considered active. Based on the last operation, we can tell that the resource is currently active. Additionally, from the presence of a ``stop`` operation with a lower ``call-id`` than that of the ``start`` operation, we can conclude that the resource has been restarted. Specifically this occurred as part of actions 11 and 31 of transition 11 from the controller instance with the key ``2668bbeb...``. This information can be helpful for locating the relevant section of the logs when looking for the source of a failure.