diff --git a/doc/sphinx/Pacemaker_Administration/administrative.rst b/doc/sphinx/Pacemaker_Administration/administrative.rst new file mode 100644 index 0000000000..7c8b346193 --- /dev/null +++ b/doc/sphinx/Pacemaker_Administration/administrative.rst @@ -0,0 +1,150 @@ +.. index:: + single: administrative mode + +Administrative Modes +-------------------- + +Intrusive administration can be performed on a Pacemaker cluster without +causing resource failures, recovery, and fencing, by putting the cluster or a +subset of it into an administrative mode. + +Pacemaker supports several administrative modes: + +* Maintenance mode for the entire cluster, specific nodes, or specific + resources +* Unmanaged resources +* Disabled configuration items +* Standby mode for specific nodes + +Rules may be used to automatically set any of these modes for specific times or +other conditions. + + +.. index:: + pair: administrative mode; maintenance mode + +.. _maintenance_mode: + +Maintenance Mode +################ + +In maintenance mode, the cluster will not start or stop resources. Recurring +monitors for affected resources will be paused, except those specifying +``role`` as ``Stopped``. + +To put a specific resource into maintenance mode, set the resource's +``maintenance`` meta-attribute to ``true``. + +To put all active resources on a specific node into maintenance mode, set the +node's ``maintenance`` node attribute to ``true``. When enabled, this overrides +resource-specific maintenance mode. + +.. warning:: + + Restarting Pacemaker on a node that is in single-node maintenance mode will + likely lead to undesirable effects. If ``maintenance`` is set as a transient + attribute, it will be erased when Pacemaker is stopped, which will + immediately take the node out of maintenance mode and likely get it fenced. + If set as a permanent attribute, any resources active on the node will have + their local history erased when Pacemaker is restarted, so the cluster will + no longer consider them running on the node and thus will consider them + managed again, allowing them to be started elsewhere. + +To put all resources in the cluster into maintenance mode, set the +``maintenance-mode`` cluster option to ``true``. When enabled, this overrides +node- or resource- specific maintenance mode. + +Maintenance mode, at any level, overrides other administrative modes. + + +.. index:: + pair: administrative mode; unmanaged resources + +.. _unmanaged_resources: + +Unmanaged Resources +################### + +An unmanaged resource will not be started or stopped by the cluster. A resource +may become unmanaged in several ways: + +* The administrator may set the ``is-managed`` resource meta-attribute to + ``false`` (whether for a specific resource, or all resources without an + explicit setting via ``rsc_defaults``) +* :ref:`Maintenance mode ` causes affected resources to + become unmanaged (and overrides any ``is-managed`` setting) +* Certain types of failure cause affected resources to become unmanaged. These + include: + + * Failed stop operations when the ``stonith-enabled`` cluster property is set + to ``false`` + * Failure of an operation that has ``on-fail`` set to ``block`` + * A resource detected as incorrectly active on more than one node when its + ``multiple-active`` meta-attribute is set to ``block`` + * A resource constrained by a revoked ``rsc_ticket`` with ``loss-policy`` set + to ``freeze`` + * Resources with ``requires`` set (or defaulting) to anything other than + ``nothing`` in a partition that loses quorum when the ``no-quorum-policy`` + cluster option is set to ``freeze`` + +Recurring actions are not affected by unmanaging a resource. + +.. warning:: + + Manually starting an unmanaged resource on a different node is strongly + discouraged. It will at least cause the cluster to consider the resource + failed, and may require the resource's ``target-role`` to be set to + ``Stopped`` then ``Started`` in order for recovery to succeed. + + +.. index:: + pair: administrative mode; disabled configuration + +.. _disabled_configuration: + +Disabled Configuration +###################### + +Some configuration elements disable particular behaviors: + +* The ``stonith-enabled`` cluster option, when set to ``false``, disables node + fencing. This is highly discouraged, as it can lead to data unavailability, + loss, or corruption. + +* The ``stop-all-resources`` cluster option, when set to ``true``, causes all + resources to be stopped. + +* Certain elements support an ``enabled`` meta-attribute, which if set to + ``false``, causes the cluster to act as if the specific element is not + configured. These include ``op``, ``alert`` *(since 2.1.6)*, and + ``recipient`` *(since 2.1.6)*. ``enabled`` may be set for specific ``op`` + elements, or all operations without an explicit setting via ``op_defaults``. + + +.. index:: + pair: administrative mode; standby + +.. _standby: + +Standby Mode +############ + +When a node is put into standby, all resources will be moved away from the +node, and all recurring operations will be stopped on the node, except those +specifying ``role`` as ``Stopped`` (which will be newly initiated if +appropriate). + +A node may be put into standby mode by setting its ``standby`` node attribute +to ``true``. The attribute may be queried and set using the ``crm_standby`` +tool. + + +.. index:: + pair: administrative mode; rules + +Rules +##### + +Rules may be used to set administrative mode options automatically according to +various criteria such as date and time. See the "Rules" chapter of the +*Pacemaker Explained* document for details. diff --git a/doc/sphinx/Pacemaker_Administration/index.rst b/doc/sphinx/Pacemaker_Administration/index.rst index 327ad31c94..af893801b6 100644 --- a/doc/sphinx/Pacemaker_Administration/index.rst +++ b/doc/sphinx/Pacemaker_Administration/index.rst @@ -1,36 +1,38 @@ Pacemaker Administration ======================== *Managing Pacemaker Clusters* Abstract -------- This document has instructions and tips for system administrators who manage high-availability clusters using Pacemaker. Table of Contents ----------------- .. toctree:: :maxdepth: 3 :numbered: intro installing cluster configuring tools + administrative + moving troubleshooting upgrading alerts agents pcs-crmsh Index ----- * :ref:`genindex` * :ref:`search` diff --git a/doc/sphinx/Pacemaker_Explained/advanced-options.rst b/doc/sphinx/Pacemaker_Administration/moving.rst similarity index 50% rename from doc/sphinx/Pacemaker_Explained/advanced-options.rst rename to doc/sphinx/Pacemaker_Administration/moving.rst index 20ab79e224..3d6a92af51 100644 --- a/doc/sphinx/Pacemaker_Explained/advanced-options.rst +++ b/doc/sphinx/Pacemaker_Administration/moving.rst @@ -1,586 +1,305 @@ -Advanced Configuration ----------------------- - -.. index:: - single: start-delay; operation attribute - single: interval-origin; operation attribute - single: interval; interval-origin - single: operation; interval-origin - single: operation; start-delay - -Specifying When Recurring Actions are Performed -############################################### - -By default, recurring actions are scheduled relative to when the resource -started. In some cases, you might prefer that a recurring action start relative -to a specific date and time. For example, you might schedule an in-depth -monitor to run once every 24 hours, and want it to run outside business hours. - -To do this, set the operation's ``interval-origin``. The cluster uses this point -to calculate the correct ``start-delay`` such that the operation will occur -at ``interval-origin`` plus a multiple of the operation interval. - -For example, if the recurring operation's interval is 24h, its -``interval-origin`` is set to 02:00, and it is currently 14:32, then the -cluster would initiate the operation after 11 hours and 28 minutes. - -The value specified for ``interval`` and ``interval-origin`` can be any -date/time conforming to the -`ISO8601 standard `_. By way of -example, to specify an operation that would run on the first Monday of -2021 and every Monday after that, you would add: - -.. topic:: Example recurring action that runs relative to base date/time - - .. code-block:: xml - - - -.. 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. +Moving Resources +---------------- .. index:: single: resource; move -Moving Resources -################ - Moving Resources Manually -_________________________ +######################### There are primarily two occasions when you would want to move a resource from its current location: when the whole node is under maintenance, and when a single resource needs to be moved. .. index:: single: standby mode single: node; standby mode Standby Mode -~~~~~~~~~~~~ +____________ Since everything eventually comes down to a score, you could create constraints for every resource to prevent them from running on one node. While Pacemaker configuration can seem convoluted at times, not even we would require this of administrators. Instead, you can set a special node attribute which tells the cluster "don't let anything run here". There is even a helpful tool to help query and set it, called ``crm_standby``. To check the standby status of the current machine, run: .. code-block:: none # crm_standby -G A value of ``on`` indicates that the node is *not* able to host any resources, while a value of ``off`` says that it *can*. You can also check the status of other nodes in the cluster by specifying the `--node` option: .. code-block:: none # crm_standby -G --node sles-2 To change the current node's standby status, use ``-v`` instead of ``-G``: .. code-block:: none # crm_standby -v on Again, you can change another host's value by supplying a hostname with ``--node``. A cluster node in standby mode will not run resources, but still contributes to quorum, and may fence or be fenced by nodes. Moving One Resource -~~~~~~~~~~~~~~~~~~~ +___________________ When only one resource is required to move, we could do this by creating location constraints. However, once again we provide a user-friendly shortcut as part of the ``crm_resource`` command, which creates and modifies the extra constraints for you. If ``Email`` were running on ``sles-1`` and you wanted it moved to a specific location, the command would look something like: .. code-block:: none # crm_resource -M -r Email -H sles-2 Behind the scenes, the tool will create the following location constraint: .. code-block:: xml It is important to note that subsequent invocations of ``crm_resource -M`` are not cumulative. So, if you ran these commands: .. code-block:: none # crm_resource -M -r Email -H sles-2 # crm_resource -M -r Email -H sles-3 then it is as if you had never performed the first command. To allow the resource to move back again, use: .. code-block:: none # crm_resource -U -r Email Note the use of the word *allow*. The resource *can* move back to its original location, but depending on ``resource-stickiness``, location constraints, and so forth, it might stay where it is. To be absolutely certain that it moves back to ``sles-1``, move it there before issuing the call to ``crm_resource -U``: .. code-block:: none # crm_resource -M -r Email -H sles-1 # crm_resource -U -r Email Alternatively, if you only care that the resource should be moved from its current location, try: .. code-block:: none # crm_resource -B -r Email which will instead create a negative constraint, like: .. code-block:: xml This will achieve the desired effect, but will also have long-term consequences. As the tool will warn you, the creation of a ``-INFINITY`` constraint will prevent the resource from running on that node until ``crm_resource -U`` is used. This includes the situation where every other cluster node is no longer available! In some cases, such as when ``resource-stickiness`` is set to ``INFINITY``, it -is possible that you will end up with the problem described in -:ref:`node-score-equal`. The tool can detect some of these cases and deals with -them by creating both positive and negative constraints. For example: +is possible that you will end up with nodes with the same score, forcing the +cluster to choose one (which may not be the one you want). The tool can detect +some of these cases and deals with them by creating both positive and negative +constraints. For example: .. code-block:: xml which has the same long-term consequences as discussed earlier. Moving Resources Due to Connectivity Changes -____________________________________________ +############################################ You can configure the cluster to move resources when external connectivity is lost in two steps. .. index:: single: ocf:pacemaker:ping resource single: ping resource Tell Pacemaker to Monitor Connectivity -~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ +______________________________________ First, add an ``ocf:pacemaker:ping`` resource to the cluster. The ``ping`` resource uses the system utility of the same name to a test whether a list of machines (specified by DNS hostname or IP address) are reachable, and uses the results to maintain a node attribute. The node attribute is called ``pingd`` by default, but is customizable in order to allow multiple ping groups to be defined. Normally, the ping resource should run on all cluster nodes, which means that you'll need to create a clone. A template for this can be found below, along with a description of the most interesting parameters. .. table:: **Commonly Used ocf:pacemaker:ping Resource Parameters** :widths: 1 4 +--------------------+--------------------------------------------------------------+ | Resource Parameter | Description | +====================+==============================================================+ | dampen | .. index:: | | | single: ocf:pacemaker:ping resource; dampen parameter | | | single: dampen; ocf:pacemaker:ping resource parameter | | | | | | The time to wait (dampening) for further changes to occur. | | | Use this to prevent a resource from bouncing around the | | | cluster when cluster nodes notice the loss of connectivity | | | at slightly different times. | +--------------------+--------------------------------------------------------------+ | multiplier | .. index:: | | | single: ocf:pacemaker:ping resource; multiplier parameter | | | single: multiplier; ocf:pacemaker:ping resource parameter | | | | | | The number of connected ping nodes gets multiplied by this | | | value to get a score. Useful when there are multiple ping | | | nodes configured. | +--------------------+--------------------------------------------------------------+ | host_list | .. index:: | | | single: ocf:pacemaker:ping resource; host_list parameter | | | single: host_list; ocf:pacemaker:ping resource parameter | | | | | | The machines to contact in order to determine the current | | | connectivity status. Allowed values include resolvable DNS | | | connectivity host names, IPv4 addresses, and IPv6 addresses. | +--------------------+--------------------------------------------------------------+ .. topic:: Example ping resource that checks node connectivity once every minute .. code-block:: xml .. important:: You're only half done. The next section deals with telling Pacemaker how to deal with the connectivity status that ``ocf:pacemaker:ping`` is recording. Tell Pacemaker How to Interpret the Connectivity Data -~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ +_____________________________________________________ .. important:: - Before attempting the following, make sure you understand - :ref:`rules`. + Before attempting the following, make sure you understand rules. See the + "Rules" chapter of the *Pacemaker Explained* document for details. There are a number of ways to use the connectivity data. The most common setup is for people to have a single ping target (for example, the service network's default gateway), to prevent the cluster from running a resource on any unconnected node. .. topic:: Don't run a resource on unconnected nodes .. code-block:: xml A more complex setup is to have a number of ping targets configured. You can require the cluster to only run resources on nodes that can connect to all (or a minimum subset) of them. .. topic:: Run only on nodes connected to three or more ping targets .. code-block:: xml ... ... ... Alternatively, you can tell the cluster only to *prefer* nodes with the best connectivity, by using ``score-attribute`` in the rule. Just be sure to set ``multiplier`` to a value higher than that of ``resource-stickiness`` (and don't set either of them to ``INFINITY``). .. topic:: Prefer node with most connected ping nodes .. code-block:: xml It is perhaps easier to think of this in terms of the simple constraints that the cluster translates it into. For example, if ``sles-1`` is connected to all five ping nodes but ``sles-2`` is only connected to two, then it would be as if you instead had the following constraints in your configuration: .. topic:: How the cluster translates the above location constraint .. code-block:: xml The advantage is that you don't have to manually update any constraints whenever your network connectivity changes. You can also combine the concepts above into something even more complex. The example below shows how you can prefer the node with the most connected ping nodes provided they have connectivity to at least three (again assuming that ``multiplier`` is set to 1000). .. topic:: More complex example of choosing location based on connectivity .. code-block:: xml - - -.. _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 resource 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. - - -.. 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. - -.. rubric:: Footnotes - -.. [#] 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/advanced-resources.rst b/doc/sphinx/Pacemaker_Explained/collective.rst similarity index 99% rename from doc/sphinx/Pacemaker_Explained/advanced-resources.rst rename to doc/sphinx/Pacemaker_Explained/collective.rst index 07583507a4..a4fa9dc65b 100644 --- a/doc/sphinx/Pacemaker_Explained/advanced-resources.rst +++ b/doc/sphinx/Pacemaker_Explained/collective.rst @@ -1,1629 +1,1637 @@ -Advanced Resource Types ------------------------ +.. 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 +-------------+------------------------------------------------------------------+ | 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 | | | | | | An optional description of the group, for the user's own | | | purposes. | | | E.g. ``resources needed for website`` | +-------------+------------------------------------------------------------------+ 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 +-------------+------------------------------------------------------------------+ | 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 | | | | | | An optional description of the clone, for the user's own | | | purposes. | | | E.g. ``IP address for website`` | +-------------+------------------------------------------------------------------+ .. 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 +-------------------+-----------------+-------------------------------------------------------+ | Field | Default | Description | +===================+=================+=======================================================+ | globally-unique | false | .. index:: | | | | single: clone; option, globally-unique | | | | single: option; globally-unique (clone) | | | | single: globally-unique; clone option | | | | | | | | If **true**, each clone instance performs a | | | | distinct function | +-------------------+-----------------+-------------------------------------------------------+ | 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 ``globally-unique`` is **true**, 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 ``promotable`` is **true** and ``globally-unique`` | | | | is **false**, the number of clone instances can be | | | | promoted at one time on a single node | +-------------------+-----------------+-------------------------------------------------------+ .. 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 a ``master`` tag, instead of a ``clone`` tag with the ``promotable`` meta-attribute set to ``true`` * 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. Clone Resource Agent Requirements _________________________________ Any resource can be used as an anonymous clone, as it requires no additional support from the resource agent. Whether it makes sense to do so depends on your resource and its resource agent. Resource Agent Requirements for Globally Unique Clones ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Globally unique clones require additional support in the resource agent. In particular, it must only respond with ``${OCF_SUCCESS}`` if the node has that exact instance active. All other probes for instances of the clone should result in ``${OCF_NOT_RUNNING}`` (or one of the other OCF error codes if they are failed). Individual instances of a clone are identified by appending a colon and a numerical offset, e.g. **apache:2**. Resource agents can find out how many copies there are by examining the ``OCF_RESKEY_CRM_meta_clone_max`` environment variable and which instance it is by examining ``OCF_RESKEY_CRM_meta_clone``. The resource agent must not make any assumptions (based on ``OCF_RESKEY_CRM_meta_clone``) about which numerical instances are active. In particular, the list of active copies will not always be an unbroken sequence, nor always start at 0. Resource Agent Requirements for Promotable Clones ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Promotable clone resources require two extra actions, ``demote`` and ``promote``, which are responsible for changing the state of the resource. Like **start** and **stop**, they should return ``${OCF_SUCCESS}`` if they completed successfully or a relevant error code if they did not. The states can mean whatever you wish, but when the resource is started, it must come up in the unpromoted role. From there, the cluster will decide which instances to promote. In addition to the clone requirements for monitor actions, agents must also *accurately* report which state they are in. The cluster relies on the agent to report its status (including role) accurately and does not indicate to the agent what role it currently believes it to be in. .. table:: **Role implications of OCF return codes** :widths: 1 3 +----------------------+--------------------------------------------------+ | Monitor Return Code | Description | +======================+==================================================+ | OCF_NOT_RUNNING | .. index:: | | | single: OCF_NOT_RUNNING | | | single: OCF return code; OCF_NOT_RUNNING | | | | | | Stopped | +----------------------+--------------------------------------------------+ | OCF_SUCCESS | .. index:: | | | single: OCF_SUCCESS | | | single: OCF return code; OCF_SUCCESS | | | | | | Running (Unpromoted) | +----------------------+--------------------------------------------------+ | OCF_RUNNING_PROMOTED | .. index:: | | | single: OCF_RUNNING_PROMOTED | | | single: OCF return code; OCF_RUNNING_PROMOTED | | | | | | Running (Promoted) | +----------------------+--------------------------------------------------+ | OCF_FAILED_PROMOTED | .. index:: | | | single: OCF_FAILED_PROMOTED | | | single: OCF return code; OCF_FAILED_PROMOTED | | | | | | Failed (Promoted) | +----------------------+--------------------------------------------------+ | Other | .. index:: | | | single: return code | | | | | | Failed (Unpromoted) | +----------------------+--------------------------------------------------+ Clone Notifications ~~~~~~~~~~~~~~~~~~~ If the clone has the ``notify`` meta-attribute set to **true**, and the resource agent supports the ``notify`` action, Pacemaker will call the action when appropriate, passing a number of extra variables which, when combined with additional context, can be used to calculate the current state of the cluster and what is about to happen to it. .. index:: single: clone; environment variables single: notify; environment variables .. table:: **Environment variables supplied with Clone notify actions** :widths: 1 1 +----------------------------------------------+-------------------------------------------------------------------------------+ | Variable | Description | +==============================================+===============================================================================+ | OCF_RESKEY_CRM_meta_notify_type | .. index:: | | | single: environment variable; OCF_RESKEY_CRM_meta_notify_type | | | single: OCF_RESKEY_CRM_meta_notify_type | | | | | | Allowed values: **pre**, **post** | +----------------------------------------------+-------------------------------------------------------------------------------+ | OCF_RESKEY_CRM_meta_notify_operation | .. index:: | | | single: environment variable; OCF_RESKEY_CRM_meta_notify_operation | | | single: OCF_RESKEY_CRM_meta_notify_operation | | | | | | Allowed values: **start**, **stop** | +----------------------------------------------+-------------------------------------------------------------------------------+ | OCF_RESKEY_CRM_meta_notify_start_resource | .. index:: | | | single: environment variable; OCF_RESKEY_CRM_meta_notify_start_resource | | | single: OCF_RESKEY_CRM_meta_notify_start_resource | | | | | | Resources to be started | +----------------------------------------------+-------------------------------------------------------------------------------+ | OCF_RESKEY_CRM_meta_notify_stop_resource | .. index:: | | | single: environment variable; OCF_RESKEY_CRM_meta_notify_stop_resource | | | single: OCF_RESKEY_CRM_meta_notify_stop_resource | | | | | | Resources to be stopped | +----------------------------------------------+-------------------------------------------------------------------------------+ | OCF_RESKEY_CRM_meta_notify_active_resource | .. index:: | | | single: environment variable; OCF_RESKEY_CRM_meta_notify_active_resource | | | single: OCF_RESKEY_CRM_meta_notify_active_resource | | | | | | Resources that are running | +----------------------------------------------+-------------------------------------------------------------------------------+ | OCF_RESKEY_CRM_meta_notify_inactive_resource | .. index:: | | | single: environment variable; OCF_RESKEY_CRM_meta_notify_inactive_resource | | | single: OCF_RESKEY_CRM_meta_notify_inactive_resource | | | | | | Resources that are not running | +----------------------------------------------+-------------------------------------------------------------------------------+ | OCF_RESKEY_CRM_meta_notify_start_uname | .. index:: | | | single: environment variable; OCF_RESKEY_CRM_meta_notify_start_uname | | | single: OCF_RESKEY_CRM_meta_notify_start_uname | | | | | | Nodes on which resources will be started | +----------------------------------------------+-------------------------------------------------------------------------------+ | OCF_RESKEY_CRM_meta_notify_stop_uname | .. index:: | | | single: environment variable; OCF_RESKEY_CRM_meta_notify_stop_uname | | | single: OCF_RESKEY_CRM_meta_notify_stop_uname | | | | | | Nodes on which resources will be stopped | +----------------------------------------------+-------------------------------------------------------------------------------+ | OCF_RESKEY_CRM_meta_notify_active_uname | .. index:: | | | single: environment variable; OCF_RESKEY_CRM_meta_notify_active_uname | | | single: OCF_RESKEY_CRM_meta_notify_active_uname | | | | | | Nodes on which resources are running | +----------------------------------------------+-------------------------------------------------------------------------------+ The variables come in pairs, such as ``OCF_RESKEY_CRM_meta_notify_start_resource`` and ``OCF_RESKEY_CRM_meta_notify_start_uname``, and should be treated as an array of whitespace-separated elements. ``OCF_RESKEY_CRM_meta_notify_inactive_resource`` is an exception, as the matching **uname** variable does not exist since inactive resources are not running on any node. Thus, in order to indicate that **clone:0** will be started on **sles-1**, **clone:2** will be started on **sles-3**, and **clone:3** will be started on **sles-2**, the cluster would set: .. topic:: Notification variables .. code-block:: none OCF_RESKEY_CRM_meta_notify_start_resource="clone:0 clone:2 clone:3" OCF_RESKEY_CRM_meta_notify_start_uname="sles-1 sles-3 sles-2" .. note:: Pacemaker will log but otherwise ignore failures of notify actions. Interpretation of Notification Variables ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ **Pre-notification (stop):** * Active resources: ``$OCF_RESKEY_CRM_meta_notify_active_resource`` * Inactive resources: ``$OCF_RESKEY_CRM_meta_notify_inactive_resource`` * Resources to be started: ``$OCF_RESKEY_CRM_meta_notify_start_resource`` * Resources to be stopped: ``$OCF_RESKEY_CRM_meta_notify_stop_resource`` **Post-notification (stop) / Pre-notification (start):** * Active resources * ``$OCF_RESKEY_CRM_meta_notify_active_resource`` * minus ``$OCF_RESKEY_CRM_meta_notify_stop_resource`` * Inactive resources * ``$OCF_RESKEY_CRM_meta_notify_inactive_resource`` * plus ``$OCF_RESKEY_CRM_meta_notify_stop_resource`` * Resources that were started: ``$OCF_RESKEY_CRM_meta_notify_start_resource`` * Resources that were stopped: ``$OCF_RESKEY_CRM_meta_notify_stop_resource`` **Post-notification (start):** * Active resources: * ``$OCF_RESKEY_CRM_meta_notify_active_resource`` * minus ``$OCF_RESKEY_CRM_meta_notify_stop_resource`` * plus ``$OCF_RESKEY_CRM_meta_notify_start_resource`` * Inactive resources: * ``$OCF_RESKEY_CRM_meta_notify_inactive_resource`` * plus ``$OCF_RESKEY_CRM_meta_notify_stop_resource`` * minus ``$OCF_RESKEY_CRM_meta_notify_start_resource`` * Resources that were started: ``$OCF_RESKEY_CRM_meta_notify_start_resource`` * Resources that were stopped: ``$OCF_RESKEY_CRM_meta_notify_stop_resource`` Extra Notifications for Promotable Clones ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ .. index:: single: clone; environment variables single: promotable; environment variables .. table:: **Extra environment variables supplied for promotable clones** :widths: 1 1 +------------------------------------------------+---------------------------------------------------------------------------------+ | Variable | Description | +================================================+=================================================================================+ | OCF_RESKEY_CRM_meta_notify_promoted_resource | .. index:: | | | single: environment variable; OCF_RESKEY_CRM_meta_notify_promoted_resource | | | single: OCF_RESKEY_CRM_meta_notify_promoted_resource | | | | | | Resources that are running in the promoted role | +------------------------------------------------+---------------------------------------------------------------------------------+ | OCF_RESKEY_CRM_meta_notify_unpromoted_resource | .. index:: | | | single: environment variable; OCF_RESKEY_CRM_meta_notify_unpromoted_resource | | | single: OCF_RESKEY_CRM_meta_notify_unpromoted_resource | | | | | | Resources that are running in the unpromoted role | +------------------------------------------------+---------------------------------------------------------------------------------+ | OCF_RESKEY_CRM_meta_notify_promote_resource | .. index:: | | | single: environment variable; OCF_RESKEY_CRM_meta_notify_promote_resource | | | single: OCF_RESKEY_CRM_meta_notify_promote_resource | | | | | | Resources to be promoted | +------------------------------------------------+---------------------------------------------------------------------------------+ | OCF_RESKEY_CRM_meta_notify_demote_resource | .. index:: | | | single: environment variable; OCF_RESKEY_CRM_meta_notify_demote_resource | | | single: OCF_RESKEY_CRM_meta_notify_demote_resource | | | | | | Resources to be demoted | +------------------------------------------------+---------------------------------------------------------------------------------+ | OCF_RESKEY_CRM_meta_notify_promote_uname | .. index:: | | | single: environment variable; OCF_RESKEY_CRM_meta_notify_promote_uname | | | single: OCF_RESKEY_CRM_meta_notify_promote_uname | | | | | | Nodes on which resources will be promoted | +------------------------------------------------+---------------------------------------------------------------------------------+ | OCF_RESKEY_CRM_meta_notify_demote_uname | .. index:: | | | single: environment variable; OCF_RESKEY_CRM_meta_notify_demote_uname | | | single: OCF_RESKEY_CRM_meta_notify_demote_uname | | | | | | Nodes on which resources will be demoted | +------------------------------------------------+---------------------------------------------------------------------------------+ | OCF_RESKEY_CRM_meta_notify_promoted_uname | .. index:: | | | single: environment variable; OCF_RESKEY_CRM_meta_notify_promoted_uname | | | single: OCF_RESKEY_CRM_meta_notify_promoted_uname | | | | | | Nodes on which resources are running in the promoted role | +------------------------------------------------+---------------------------------------------------------------------------------+ | OCF_RESKEY_CRM_meta_notify_unpromoted_uname | .. index:: | | | single: environment variable; OCF_RESKEY_CRM_meta_notify_unpromoted_uname | | | single: OCF_RESKEY_CRM_meta_notify_unpromoted_uname | | | | | | Nodes on which resources are running in the unpromoted role | +------------------------------------------------+---------------------------------------------------------------------------------+ Interpretation of Promotable Notification Variables ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ **Pre-notification (demote):** * Active resources: ``$OCF_RESKEY_CRM_meta_notify_active_resource`` * Promoted resources: ``$OCF_RESKEY_CRM_meta_notify_promoted_resource`` * Unpromoted resources: ``$OCF_RESKEY_CRM_meta_notify_unpromoted_resource`` * Inactive resources: ``$OCF_RESKEY_CRM_meta_notify_inactive_resource`` * Resources to be started: ``$OCF_RESKEY_CRM_meta_notify_start_resource`` * Resources to be promoted: ``$OCF_RESKEY_CRM_meta_notify_promote_resource`` * Resources to be demoted: ``$OCF_RESKEY_CRM_meta_notify_demote_resource`` * Resources to be stopped: ``$OCF_RESKEY_CRM_meta_notify_stop_resource`` **Post-notification (demote) / Pre-notification (stop):** * Active resources: ``$OCF_RESKEY_CRM_meta_notify_active_resource`` * Promoted resources: * ``$OCF_RESKEY_CRM_meta_notify_promoted_resource`` * minus ``$OCF_RESKEY_CRM_meta_notify_demote_resource`` * Unpromoted resources: ``$OCF_RESKEY_CRM_meta_notify_unpromoted_resource`` * Inactive resources: ``$OCF_RESKEY_CRM_meta_notify_inactive_resource`` * Resources to be started: ``$OCF_RESKEY_CRM_meta_notify_start_resource`` * Resources to be promoted: ``$OCF_RESKEY_CRM_meta_notify_promote_resource`` * Resources to be demoted: ``$OCF_RESKEY_CRM_meta_notify_demote_resource`` * Resources to be stopped: ``$OCF_RESKEY_CRM_meta_notify_stop_resource`` * Resources that were demoted: ``$OCF_RESKEY_CRM_meta_notify_demote_resource`` **Post-notification (stop) / Pre-notification (start)** * Active resources: * ``$OCF_RESKEY_CRM_meta_notify_active_resource`` * minus ``$OCF_RESKEY_CRM_meta_notify_stop_resource`` * Promoted resources: * ``$OCF_RESKEY_CRM_meta_notify_promoted_resource`` * minus ``$OCF_RESKEY_CRM_meta_notify_demote_resource`` * Unpromoted resources: * ``$OCF_RESKEY_CRM_meta_notify_unpromoted_resource`` * minus ``$OCF_RESKEY_CRM_meta_notify_stop_resource`` * Inactive resources: * ``$OCF_RESKEY_CRM_meta_notify_inactive_resource`` * plus ``$OCF_RESKEY_CRM_meta_notify_stop_resource`` * Resources to be started: ``$OCF_RESKEY_CRM_meta_notify_start_resource`` * Resources to be promoted: ``$OCF_RESKEY_CRM_meta_notify_promote_resource`` * Resources to be demoted: ``$OCF_RESKEY_CRM_meta_notify_demote_resource`` * Resources to be stopped: ``$OCF_RESKEY_CRM_meta_notify_stop_resource`` * Resources that were demoted: ``$OCF_RESKEY_CRM_meta_notify_demote_resource`` * Resources that were stopped: ``$OCF_RESKEY_CRM_meta_notify_stop_resource`` **Post-notification (start) / Pre-notification (promote)** * Active resources: * ``$OCF_RESKEY_CRM_meta_notify_active_resource`` * minus ``$OCF_RESKEY_CRM_meta_notify_stop_resource`` * plus ``$OCF_RESKEY_CRM_meta_notify_start_resource`` * Promoted resources: * ``$OCF_RESKEY_CRM_meta_notify_promoted_resource`` * minus ``$OCF_RESKEY_CRM_meta_notify_demote_resource`` * Unpromoted resources: * ``$OCF_RESKEY_CRM_meta_notify_unpromoted_resource`` * minus ``$OCF_RESKEY_CRM_meta_notify_stop_resource`` * plus ``$OCF_RESKEY_CRM_meta_notify_start_resource`` * Inactive resources: * ``$OCF_RESKEY_CRM_meta_notify_inactive_resource`` * plus ``$OCF_RESKEY_CRM_meta_notify_stop_resource`` * minus ``$OCF_RESKEY_CRM_meta_notify_start_resource`` * Resources to be started: ``$OCF_RESKEY_CRM_meta_notify_start_resource`` * Resources to be promoted: ``$OCF_RESKEY_CRM_meta_notify_promote_resource`` * Resources to be demoted: ``$OCF_RESKEY_CRM_meta_notify_demote_resource`` * Resources to be stopped: ``$OCF_RESKEY_CRM_meta_notify_stop_resource`` * Resources that were started: ``$OCF_RESKEY_CRM_meta_notify_start_resource`` * Resources that were demoted: ``$OCF_RESKEY_CRM_meta_notify_demote_resource`` * Resources that were stopped: ``$OCF_RESKEY_CRM_meta_notify_stop_resource`` **Post-notification (promote)** * Active resources: * ``$OCF_RESKEY_CRM_meta_notify_active_resource`` * minus ``$OCF_RESKEY_CRM_meta_notify_stop_resource`` * plus ``$OCF_RESKEY_CRM_meta_notify_start_resource`` * Promoted resources: * ``$OCF_RESKEY_CRM_meta_notify_promoted_resource`` * minus ``$OCF_RESKEY_CRM_meta_notify_demote_resource`` * plus ``$OCF_RESKEY_CRM_meta_notify_promote_resource`` * Unpromoted resources: * ``$OCF_RESKEY_CRM_meta_notify_unpromoted_resource`` * minus ``$OCF_RESKEY_CRM_meta_notify_stop_resource`` * plus ``$OCF_RESKEY_CRM_meta_notify_start_resource`` * minus ``$OCF_RESKEY_CRM_meta_notify_promote_resource`` * Inactive resources: * ``$OCF_RESKEY_CRM_meta_notify_inactive_resource`` * plus ``$OCF_RESKEY_CRM_meta_notify_stop_resource`` * minus ``$OCF_RESKEY_CRM_meta_notify_start_resource`` * Resources to be started: ``$OCF_RESKEY_CRM_meta_notify_start_resource`` * Resources to be promoted: ``$OCF_RESKEY_CRM_meta_notify_promote_resource`` * Resources to be demoted: ``$OCF_RESKEY_CRM_meta_notify_demote_resource`` * Resources to be stopped: ``$OCF_RESKEY_CRM_meta_notify_stop_resource`` * Resources that were started: ``$OCF_RESKEY_CRM_meta_notify_start_resource`` * Resources that were promoted: ``$OCF_RESKEY_CRM_meta_notify_promote_resource`` * Resources that were demoted: ``$OCF_RESKEY_CRM_meta_notify_demote_resource`` * Resources that were stopped: ``$OCF_RESKEY_CRM_meta_notify_stop_resource`` 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 pair: container; rkt .. _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 `_, `podman `_ *(since 2.0.1)*, and `rkt `_ 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, podman, or rkt), 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**, **ocf:heartbeat:podman**, or **ocf:heartbeat:rkt** 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 +-------------+------------------------------------------------------------------+ | 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 | | | | | | An optional description of the group, for the user's own | | | purposes. | | | E.g. ``manages the container that runs the service`` | +-------------+------------------------------------------------------------------+ A bundle must contain exactly one ``docker``, ``podman``, or ``rkt`` element. .. index:: pair: XML element; docker pair: XML element; podman pair: XML element; rkt Bundle Container Properties ___________________________ .. table:: **XML attributes of a docker, podman, or rkt Element** :class: longtable :widths: 2 3 4 +-------------------+------------------------------------+---------------------------------------------------+ | 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 | | | | single: rkt; attribute, image | | | | single: attribute; image (rkt) | | | | single: image; rkt 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 | | | | single: rkt; attribute, replicas | | | | single: attribute; replicas (rkt) | | | | single: replicas; rkt 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 | | | | single: rkt; attribute, replicas-per-host | | | | single: attribute; replicas-per-host (rkt) | | | | single: replicas-per-host; rkt 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 | | | | single: rkt; attribute, promoted-max | | | | single: attribute; promoted-max (rkt) | | | | single: promoted-max; rkt 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 | | | | single: rkt; attribute, network | | | | single: attribute; network (rkt) | | | | single: network; rkt attribute | | | | | | | | If specified, this will be passed to the | | | | ``docker run``, ``podman run``, or | | | | ``rkt 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 | | | | single: rkt; attribute, run-command | | | | single: attribute; run-command (rkt) | | | | single: run-command; rkt 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 | | | | single: rkt; attribute, options | | | | single: attribute; options (rkt) | | | | single: options; rkt attribute | | | | | | | | Extra command-line options to pass to the | | | | ``docker run``, ``podman run``, or ``rkt 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 +----------------+---------+------------------------------------------------------------+ | 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 +---------------+-------------------+------------------------------------------------------+ | 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 +-----------------+---------+-------------------------------------------------------------+ | 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 902f1d069e..a78d6c2bb1 100644 --- a/doc/sphinx/Pacemaker_Explained/constraints.rst +++ b/doc/sphinx/Pacemaker_Explained/constraints.rst @@ -1,1120 +1,1077 @@ .. index:: single: constraint single: resource; constraint .. _constraints: Resource Constraints -------------------- -.. index:: - single: resource; score - single: node; score - -Scores -###### - -Scores of all kinds are integral to how the cluster 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. - -Infinity Math -_____________ - -Pacemaker implements **INFINITY** (or equivalently, **+INFINITY**) internally as a -score of 1,000,000. Addition and subtraction with it follow these three basic -rules: - -* Any value + **INFINITY** = **INFINITY** - -* Any value - **INFINITY** = -**INFINITY** - -* **INFINITY** - **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). - .. _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 ___________________ .. table:: **Attributes of a rsc_location Element** :class: longtable :widths: 1 1 4 +--------------------+---------+----------------------------------------------------------------------------------------------+ | Attribute | Default | Description | +====================+=========+==============================================================================================+ | id | | .. index:: | | | | single: rsc_location; attribute, id | | | | single: attribute; id (rsc_location) | | | | single: id; rsc_location attribute | | | | | | | | A unique name for the constraint (required) | +--------------------+---------+----------------------------------------------------------------------------------------------+ | rsc | | .. index:: | | | | single: rsc_location; attribute, rsc | | | | single: attribute; rsc (rsc_location) | | | | single: rsc; rsc_location attribute | | | | | | | | 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 | | | | | | | | 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 is governed by | | | | 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. | +--------------------+---------+----------------------------------------------------------------------------------------------+ | node | | .. index:: | | | | single: rsc_location; attribute, node | | | | single: attribute; node (rsc_location) | | | | single: node; rsc_location attribute | | | | | | | | 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. | +--------------------+---------+----------------------------------------------------------------------------------------------+ | score | | .. index:: | | | | single: rsc_location; attribute, score | | | | single: attribute; score (rsc_location) | | | | single: score; rsc_location attribute | | | | | | | | 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. | +--------------------+---------+----------------------------------------------------------------------------------------------+ | resource-discovery | always | .. index:: | | | | single: rsc_location; attribute, resource-discovery | | | | single: attribute; resource-discovery (rsc_location) | | | | single: resource-discovery; rsc_location attribute | | | | | | | | 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. | | | | | | | | * ``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 +--------------+----------------------------+-------------------------------------------------------------------+ | 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 +----------------+----------------+--------------------------------------------------------+ | 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 +-------------+------------------+--------------------------------------------------------+ | 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 | value of | .. index:: | | | ``first-action`` | single: resource_set; attribute, action | | | in the enclosing | single: attribute; action (resource_set) | | | ordering | single: action; resource_set attribute | | | constraint | | | | | 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 within the constraint. | +-------------+------------------+--------------------------------------------------------+ .. _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/index.rst b/doc/sphinx/Pacemaker_Explained/index.rst index 36504b66e5..e3b7e9e55e 100644 --- a/doc/sphinx/Pacemaker_Explained/index.rst +++ b/doc/sphinx/Pacemaker_Explained/index.rst @@ -1,42 +1,41 @@ Pacemaker Explained =================== *Configuring Pacemaker Clusters* Abstract -------- This document definitively explains Pacemaker's features and capabilities, particularly the XML syntax used in Pacemaker's Cluster Information Base (CIB). Table of Contents ----------------- .. toctree:: :maxdepth: 3 :numbered: intro options nodes resources operations constraints fencing alerts rules - advanced-options - advanced-resources + collective reusing-configuration utilization acls status multi-site-clusters ap-samples Index ----- * :ref:`genindex` * :ref:`search` diff --git a/doc/sphinx/Pacemaker_Explained/nodes.rst b/doc/sphinx/Pacemaker_Explained/nodes.rst index 6fcadb378a..378b067177 100644 --- a/doc/sphinx/Pacemaker_Explained/nodes.rst +++ b/doc/sphinx/Pacemaker_Explained/nodes.rst @@ -1,441 +1,435 @@ Cluster Nodes ------------- Defining a Cluster 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 In normal circumstances, the admin should let the cluster populate this information automatically from the cluster layer. .. _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 Corosync node's name, in order of most preferred first: * The value of ``name`` in the ``nodelist`` section of ``corosync.conf`` * The value of ``ring0_addr`` in the ``nodelist`` section of ``corosync.conf`` * The local hostname (value of ``uname -n``) 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; 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. + +.. _special_node_attributes: + 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 +----------------------------+-----------------------------------------------------+ | 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 | .. index:: | - | | pair: node attribute; maintenance | + | maintenance | .. _node_maintenance: | | | | - | | Similar to the ``maintenance-mode`` | - | | :ref:`cluster option `, but | - | | for a single node. If true, resources will | - | | not be started or stopped on the node, | - | | resources and individual clone instances | - | | running on the node will become unmanaged, | - | | and any recurring operations for those will | - | | be cancelled. | + | | .. index:: | + | | pair: node attribute; maintenance | | | | - | | **Warning:** Restarting pacemaker on a node that is | - | | in single-node maintenance mode will likely | - | | lead to undesirable effects. If | - | | ``maintenance`` is set as a transient | - | | attribute, it will be erased when | - | | Pacemaker is stopped, which will | - | | immediately take the node out of | - | | maintenance mode and likely get it | - | | fenced. Even if permanent, if Pacemaker | - | | is restarted, any resources active on the | - | | node will have their local history erased | - | | when the node rejoins, so the cluster | - | | will no longer consider them running on | - | | the node and thus will consider them | - | | managed again, leading them to be started | - | | elsewhere. This behavior might be | - | | improved in a future release. | + | | 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 +------------+--------------------------------------------------------------+ | 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 becoming unhealthy | +------------+--------------------------------------------------------------+ | ``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) | +------------+--------------------------------------------------------------+ .. 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 +----------------+----------------------------------------------------------+ | 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 ddc43cde34..b1ad65da14 100644 --- a/doc/sphinx/Pacemaker_Explained/operations.rst +++ b/doc/sphinx/Pacemaker_Explained/operations.rst @@ -1,385 +1,623 @@ .. 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 #################### Operation properties may be specified directly in the ``op`` element as XML attributes, or in a separate ``meta_attributes`` block as ``nvpair`` elements. XML attributes take precedence over ``nvpair`` elements if both are specified. .. table:: **Properties of an Operation** :class: longtable :widths: 1 2 3 +----------------+-----------------------------------+-----------------------------------------------------+ | Field | Default | Description | +================+===================================+=====================================================+ | id | | .. index:: | | | | single: id; action property | | | | single: action; property, id | | | | | | | | A unique name for the operation. | +----------------+-----------------------------------+-----------------------------------------------------+ | name | | .. index:: | | | | single: name; action property | | | | single: action; property, name | | | | | | | | The action to perform. This can be any action | | | | supported by the agent; common values include | | | | ``monitor``, ``start``, and ``stop``. | +----------------+-----------------------------------+-----------------------------------------------------+ | interval | 0 | .. index:: | | | | single: interval; action property | | | | single: action; property, interval | | | | | | | | How frequently (in seconds) to perform the | | | | operation. A value of 0 means "when needed". | | | | A positive value defines a *recurring action*, | | | | which is typically used with | | | | :ref:`monitor `. | +----------------+-----------------------------------+-----------------------------------------------------+ | timeout | | .. index:: | | | | single: timeout; action property | | | | single: action; property, timeout | | | | | | | | How long to wait before declaring the action | | | | has failed | +----------------+-----------------------------------+-----------------------------------------------------+ | on-fail | Varies by action: | .. index:: | | | | single: on-fail; action property | | | * ``stop``: ``fence`` if | single: action; property, on-fail | | | ``stonith-enabled`` is true | | | | or ``block`` otherwise | The action to take if this action ever fails. | | | * ``demote``: ``on-fail`` of the | Allowed values: | | | ``monitor`` action with | | | | ``role`` set to ``Promoted``, | * ``ignore:`` Pretend the resource did not fail. | | | if present, enabled, and | * ``block:`` Don't perform any further operations | | | configured to a value other | on the resource. | | | than ``demote``, or ``restart`` | * ``stop:`` Stop the resource and do not start | | | otherwise | it elsewhere. | | | * all other actions: ``restart`` | * ``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 (possibly on a different node). | | | | * ``fence:`` STONITH the node on which the | | | | resource failed. | | | | * ``standby:`` Move *all* resources away from the | | | | node on which the resource failed. | +----------------+-----------------------------------+-----------------------------------------------------+ - | enabled | TRUE | .. index:: | + | enabled | TRUE | .. _op_enabled: | + | | | | + | | | .. index:: | | | | single: enabled; action property | | | | single: action; property, enabled | | | | | | | | If ``false``, ignore this operation definition. | - | | | This is typically used to pause a particular | - | | | recurring ``monitor`` operation; for instance, it | - | | | can complement the respective resource being | - | | | unmanaged (``is-managed=false``), as this alone | - | | | will :ref:`not block any configured monitoring | - | | | `. Disabling the operation | - | | | does not suppress all actions of the given type. | - | | | Allowed values: ``true``, ``false``. | + | | | 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 this | + | | | monitors, overrides this setting. Allowed values: | + | | | ``true``, ``false``. | +----------------+-----------------------------------+-----------------------------------------------------+ | record-pending | TRUE | .. index:: | | | | single: record-pending; action property | | | | single: action; property, record-pending | | | | | | | | If ``true``, the intention to perform the operation | | | | is recorded so that GUIs and CLI tools can indicate | | | | that an operation is in progress. This is best set | | | | as an *operation default* | | | | (see :ref:`s-operation-defaults`). Allowed values: | | | | ``true``, ``false``. | +----------------+-----------------------------------+-----------------------------------------------------+ | role | | .. index:: | | | | single: role; action property | | | | single: action; property, role | | | | | | | | Run the operation only on node(s) that the cluster | | | | thinks should be in the specified role. This only | | | | makes sense for recurring ``monitor`` operations. | | | | Allowed (case-sensitive) values: ``Stopped``, | | | | ``Started``, and in the case of :ref:`promotable | | | | clone resources `, | | | | ``Unpromoted`` and ``Promoted``. | +----------------+-----------------------------------+-----------------------------------------------------+ .. 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. -.. _s-monitoring-unmanaged: - -Monitoring Resources When Administration is Disabled -#################################################### - -Recurring ``monitor`` operations behave differently under various administrative -settings: - -* When a resource is unmanaged (by setting ``is-managed=false``): No monitors - will be stopped. - - If the unmanaged resource is stopped on a node where the cluster thinks it - should be running, the cluster will detect and report that it is not, but it - will not consider the monitor failed, and will not try to start the resource - until it is managed again. - - Starting the unmanaged resource on a different node is strongly discouraged - and will at least cause the cluster to consider the resource failed, and - may require the resource's ``target-role`` to be set to ``Stopped`` then - ``Started`` to be recovered. - -* When a resource is put into maintenance mode (by setting - ``maintenance=true``): The resource will be marked as unmanaged. (This - overrides ``is-managed=true``.) - - Additionally, all monitor operations will be stopped, except those specifying - ``role`` as ``Stopped`` (which will be newly initiated if appropriate). As - with unmanaged resources in general, starting a resource on a node other than - where the cluster expects it to be will cause problems. - -* When a node is put into standby: All resources will be moved away from the - node, and all ``monitor`` operations will be stopped on the node, except those - specifying ``role`` as ``Stopped`` (which will be newly initiated if - appropriate). - -* When a node is put into maintenance mode: All resources that are active on the - node will be marked as in maintenance mode. See above for more details. - -* When the cluster is put into maintenance mode: All resources in the cluster - will be marked as in maintenance mode. See above for more details. - -A resource is in maintenance mode if the cluster, the node where the resource -is active, or the resource itself is configured to be in maintenance mode. If a -resource is in maintenance mode, then it is also unmanaged. However, if a -resource is unmanaged, it is not necessarily in maintenance mode. .. _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: start-delay; operation attribute + single: interval-origin; operation attribute + single: interval; interval-origin + single: operation; interval-origin + single: operation; start-delay + +Specifying When Recurring Actions are Performed +############################################### + +By default, recurring actions are scheduled relative to when the resource +started. In some cases, you might prefer that a recurring action start relative +to a specific date and time. For example, you might schedule an in-depth +monitor to run once every 24 hours, and want it to run outside business hours. + +To do this, set the operation's ``interval-origin``. The cluster uses this point +to calculate the correct ``start-delay`` such that the operation will occur +at ``interval-origin`` plus a multiple of the operation interval. + +For example, if the recurring operation's interval is 24h, its +``interval-origin`` is set to 02:00, and it is currently 14:32, then the +cluster would initiate the operation after 11 hours and 28 minutes. + +The value specified for ``interval`` and ``interval-origin`` can be any +date/time conforming to the +`ISO8601 standard `_. By way of +example, to specify an operation that would run on the first Monday of +2021 and every Monday after that, you would add: + +.. topic:: Example recurring action that runs relative to base date/time + + .. code-block:: xml + + + + +.. 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/options.rst b/doc/sphinx/Pacemaker_Explained/options.rst index 201b2f6f7e..6436c17443 100644 --- a/doc/sphinx/Pacemaker_Explained/options.rst +++ b/doc/sphinx/Pacemaker_Explained/options.rst @@ -1,650 +1,802 @@ 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. +Configuration Value Types +######################### + +Throughout this document, configuration values will be designated as having one +of the following types: + +.. table:: **Configuration Value Types** + :class: longtable + :widths: 1 3 + + +-------------------+-------------------------------------------------------+ + | Type | Description | + +===================+=======================================================+ + | boolean | .. _boolean: | + | | | + | | .. index:: | + | | pair: type; boolean | + | | | + | | Case-insensitive true/false value where "1", "yes", | + | | "y", "on", and "true" evaluate as true and "0", "no", | + | | "n", "off", "false", and unset evaluate as false | + +-------------------+-------------------------------------------------------+ + | date/time | .. _date_time: | + | | | + | | .. index:: | + | | pair: type; date/time | + | | | + | | Textual timestamp like "Sat Dec 21 11:47:45 2013" | + +-------------------+-------------------------------------------------------+ + | enumeration | .. _enumeration: | + | | | + | | .. index:: | + | | pair: type; enumeration | + | | | + | | Text that must be one of a set of defined values | + | | (which will be listed in the description) | + +-------------------+-------------------------------------------------------+ + | integer | .. _integer: | + | | | + | | .. index:: | + | | pair: type; integer | + | | | + | | 32-bit signed integer value (-2,147,483,648 to | + | | 2,147,483,647) | + +-------------------+-------------------------------------------------------+ + | nonnegative | .. _nonnegative_integer: | + | integer | | + | | .. index:: | + | | pair: type; nonnegative integer | + | | | + | | 32-bit nonnegative integer value (0 to 2,147,483,647) | + +-------------------+-------------------------------------------------------+ + | port | .. _port: | + | | | + | | .. index:: | + | | pair: type; port | + | | | + | | Integer TCP port number (0 to 65535) | + +-------------------+-------------------------------------------------------+ + | score | .. _score: | + | | | + | | .. index:: | + | | pair: type; 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 | .. _text: | + | | | + | | .. index:: | + | | pair: type; text | + | | | + | | A text string | + +-------------------+-------------------------------------------------------+ + | version | .. _version: | + | | | + | | .. index:: | + | | pair: type; version | + | | | + | | Version number (three integers separated by dots) | + +-------------------+-------------------------------------------------------+ + +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). + + 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. -.. table:: **CIB Properties** +.. list-table:: **CIB Properties** :class: longtable - :widths: 1 3 + :widths: 2 2 2 5 + :header-rows: 1 + + * - Attribute + - 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. - +-------------------+-----------------------------------------------------------+ - | Attribute | Description | - +===================+===========================================================+ - | admin_epoch | .. index:: | - | | pair: admin_epoch; cib | - | | | - | | When a node joins the cluster, the cluster performs a | - | | check to see which node has the best configuration. It | - | | asks the node with the highest (``admin_epoch``, | - | | ``epoch``, ``num_updates``) tuple to replace the | - | | configuration on all the nodes -- which makes setting | - | | them, and 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. | - | | | - | | **Warning:** Never set this value to zero. In such cases, | - | | the cluster cannot tell the difference between your | - | | configuration and the "empty" one used when nothing is | - | | found on disk. | - +-------------------+-----------------------------------------------------------+ - | epoch | .. index:: | - | | pair: epoch; cib | - | | | - | | The cluster increments this every time the configuration | - | | is updated (usually by the administrator). | - +-------------------+-----------------------------------------------------------+ - | num_updates | .. index:: | - | | pair: num_updates; cib | - | | | - | | The cluster increments this every time the configuration | - | | or status is updated (usually by the cluster) and resets | - | | it to 0 when epoch changes. | - +-------------------+-----------------------------------------------------------+ - | validate-with | .. index:: | - | | pair: validate-with; cib | - | | | - | | Determines the type of XML validation that will be done | - | | on the configuration. If set to ``none``, the cluster | - | | will not verify that updates conform to the DTD (nor | - | | reject ones that don't). | - +-------------------+-----------------------------------------------------------+ - | remote-tls-port | .. index:: | - | | pair: remote-tls-port; cib | - | | | - | | If set to a TCP port number, the CIB manager will listen | - | | for anonymously encrypted remote connections on this | - | | port, to allow for 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 | - | | | - | | 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 | - | | | - | | Indicates when the configuration was last written to | - | | disk. Maintained by the cluster; for informational | - | | purposes only. | - +-------------------+-----------------------------------------------------------+ - | have-quorum | .. index:: | - | | pair: have-quorum; cib | - | | | - | | Indicates if the cluster has quorum. If false, this may | - | | mean that the cluster cannot start resources or fence | - | | other nodes (see ``no-quorum-policy`` below). Maintained | - | | by the cluster. | - +-------------------+-----------------------------------------------------------+ - | dc-uuid | .. index:: | - | | pair: dc-uuid; cib | - | | | - | | Indicates which cluster node is the current leader. Used | - | | by the cluster when placing resources and determining the | - | | order of some events. Maintained by the cluster. | - +-------------------+-----------------------------------------------------------+ .. _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. .. table:: **Cluster Options** :class: longtable :widths: 2 1 4 +---------------------------+---------+----------------------------------------------------+ | Option | Default | Description | +===========================+=========+====================================================+ | cluster-name | | .. index:: | | | | pair: cluster option; cluster-name | | | | | | | | An (optional) name for the cluster as a whole. | | | | This is mostly for users' convenience for use | | | | as desired in administration, but this 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 | | | | | | | | Version of Pacemaker on the cluster's DC. | | | | Determined automatically by the cluster. Often | | | | includes the hash which identifies the exact | | | | Git changeset it was built from. Used for | | | | diagnostic purposes. | +---------------------------+---------+----------------------------------------------------+ | cluster-infrastructure | | .. index:: | | | | pair: cluster option; cluster-infrastructure | | | | | | | | The messaging stack on which Pacemaker is | | | | currently running. Determined automatically by | | | | the cluster. Used for informational and | | | | diagnostic purposes. | +---------------------------+---------+----------------------------------------------------+ | no-quorum-policy | stop | .. index:: | | | | pair: cluster option; no-quorum-policy | | | | | | | | 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)* | | | | * ``suicide:`` fence all nodes in the affected | | | | cluster partition | +---------------------------+---------+----------------------------------------------------+ | batch-limit | 0 | .. index:: | | | | pair: cluster option; batch-limit | | | | | | | | The maximum number of actions that the cluster | | | | may execute in parallel across all nodes. The | | | | "correct" 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 | -1 | .. index:: | | | | pair: cluster option; migration-limit | | | | | | | | 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. | +---------------------------+---------+----------------------------------------------------+ | symmetric-cluster | true | .. index:: | | | | pair: cluster option; symmetric-cluster | | | | | | | | Whether 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 | false | .. index:: | | | | pair: cluster option; stop-all-resources | | | | | | | | Whether all resources should be disallowed from | | | | running (can be useful during maintenance) | +---------------------------+---------+----------------------------------------------------+ | stop-orphan-resources | true | .. index:: | | | | pair: cluster option; stop-orphan-resources | | | | | | | | Whether resources that have been deleted from | | | | the configuration should be stopped. This value | - | | | takes precedence over ``is-managed`` (that is, | - | | | even unmanaged resources will be stopped when | - | | | orphaned if this value is ``true`` | + | | | takes precedence over | + | | | :ref:`is-managed ` (that is, even | + | | | unmanaged resources will be stopped when orphaned | + | | | if this value is ``true``). | +---------------------------+---------+----------------------------------------------------+ | stop-orphan-actions | true | .. index:: | | | | pair: cluster option; stop-orphan-actions | | | | | | | | Whether recurring :ref:`operations ` | | | | that have been deleted from the configuration | | | | should be cancelled | +---------------------------+---------+----------------------------------------------------+ | start-failure-is-fatal | true | .. index:: | | | | pair: cluster option; start-failure-is-fatal | | | | | | | | 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 | | | | :ref:`migration-threshold `. | +---------------------------+---------+----------------------------------------------------+ | enable-startup-probes | true | .. index:: | | | | pair: cluster option; enable-startup-probes | | | | | | | | Whether the cluster should check the | | | | pre-existing state of resources when the cluster | | | | starts | +---------------------------+---------+----------------------------------------------------+ - | maintenance-mode | false | .. index:: | + | maintenance-mode | false | .. _maintenance_mode: | + | | | | + | | | .. index:: | | | | pair: cluster option; maintenance-mode | | | | | - | | | Whether the cluster should refrain from | - | | | monitoring, starting and stopping resources | + | | | 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 | true | .. index:: | | | | pair: cluster option; stonith-enabled | | | | | | | | Whether the cluster is allowed to fence nodes | | | | (for example, failed nodes and nodes with | - | | | resources that can't be stopped. | + | | | 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. | +---------------------------+---------+----------------------------------------------------+ | stonith-action | reboot | .. index:: | | | | pair: cluster option; stonith-action | | | | | | | | Action the cluster should send to the fence agent | | | | when a node must be fenced. Allowed values are | | | | ``reboot``, ``off``, and (for legacy agents only) | | | | ``poweroff``. | +---------------------------+---------+----------------------------------------------------+ | stonith-timeout | 60s | .. index:: | | | | pair: cluster option; stonith-timeout | | | | | | | | How long to wait for ``on``, ``off``, and | | | | ``reboot`` fence actions to complete by default. | +---------------------------+---------+----------------------------------------------------+ | stonith-max-attempts | 10 | .. index:: | | | | pair: cluster option; stonith-max-attempts | | | | | | | | How many times fencing can fail for a target | | | | before the cluster will no longer immediately | | | | re-attempt it. | +---------------------------+---------+----------------------------------------------------+ | stonith-watchdog-timeout | 0 | .. index:: | | | | pair: cluster option; stonith-watchdog-timeout | | | | | | | | If nonzero, and the cluster detects | | | | ``have-watchdog`` as ``true``, then watchdog-based | | | | self-fencing will be performed via SBD when | | | | fencing is required, without requiring a fencing | | | | resource explicitly configured. | | | | | | | | If this is set to a positive value, unseen nodes | | | | are assumed to self-fence within this much time. | | | | | | | | **Warning:** It must be ensured that this value is | | | | larger than the ``SBD_WATCHDOG_TIMEOUT`` | | | | environment variable on all nodes. Pacemaker | | | | verifies the settings individually on all nodes | | | | and prevents startup or shuts down if configured | | | | wrongly on the fly. It is strongly recommended | | | | that ``SBD_WATCHDOG_TIMEOUT`` be set to the same | | | | value on all nodes. | | | | | | | | If this is set to a negative value, and | | | | ``SBD_WATCHDOG_TIMEOUT`` is set, twice that value | | | | will be used. | | | | | | | | **Warning:** In this case, it is essential (and | | | | currently not verified by pacemaker) that | | | | ``SBD_WATCHDOG_TIMEOUT`` is set to the same | | | | value on all nodes. | +---------------------------+---------+----------------------------------------------------+ | concurrent-fencing | false | .. index:: | | | | pair: cluster option; concurrent-fencing | | | | | | | | 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 | stop | .. index:: | | | | pair: cluster option; fence-reaction | | | | | | | | How should a cluster node react if notified of its | | | | own fencing? A cluster node may receive | | | | notification of its own fencing 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 | 0 | .. index:: | | | | pair: cluster option; priority-fencing-delay | | | | | | | | 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 | 10min | .. index:: | | | | pair: cluster option; node-pending-timeout | | | | | | | | A node that has joined the cluster can be pending | | | | on joining the process group. We wait up to this | | | | much time for it. If it times out, fencing | | | | targeting the node will be issued if enabled. | | | | *(since 2.1.7)* | +---------------------------+---------+----------------------------------------------------+ | cluster-delay | 60s | .. index:: | | | | pair: cluster option; cluster-delay | | | | | | | | Estimated maximum round-trip delay over the | | | | network (excluding action execution). 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 in this time | | | | (after considering the action's own timeout). The | | | | "correct" value will depend on the speed and load | | | | of your network and cluster nodes. | +---------------------------+---------+----------------------------------------------------+ | dc-deadtime | 20s | .. index:: | | | | pair: cluster option; dc-deadtime | | | | | | | | How long to wait for a response from other nodes | | | | during startup. The "correct" value will depend on | | | | the speed/load of your network and the type of | | | | switches used. | +---------------------------+---------+----------------------------------------------------+ | cluster-ipc-limit | 500 | .. index:: | | | | pair: cluster option; cluster-ipc-limit | | | | | | | | 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" messages for cluster daemon PIDs | | | | in the logs. | +---------------------------+---------+----------------------------------------------------+ | pe-error-series-max | -1 | .. index:: | | | | pair: cluster option; pe-error-series-max | | | | | | | | The number of scheduler inputs resulting in errors | | | | to save. Used when reporting problems. A value of | | | | -1 means unlimited (report all), and 0 means none. | +---------------------------+---------+----------------------------------------------------+ | pe-warn-series-max | 5000 | .. index:: | | | | pair: cluster option; pe-warn-series-max | | | | | | | | The number of scheduler inputs resulting in | | | | warnings to save. Used when reporting problems. A | | | | value of -1 means unlimited (report all), and 0 | | | | means none. | +---------------------------+---------+----------------------------------------------------+ | pe-input-series-max | 4000 | .. index:: | | | | pair: cluster option; pe-input-series-max | | | | | | | | The number of "normal" scheduler inputs to save. | | | | Used when reporting problems. A value of -1 means | | | | unlimited (report all), and 0 means none. | +---------------------------+---------+----------------------------------------------------+ | enable-acl | false | .. index:: | | | | pair: cluster option; enable-acl | | | | | | | | Whether :ref:`acl` should be used to authorize | | | | modifications to the CIB | +---------------------------+---------+----------------------------------------------------+ | placement-strategy | default | .. index:: | | | | pair: cluster option; placement-strategy | | | | | | | | How the cluster should assign resources to nodes | | | | (see :ref:`utilization`). Allowed values are | | | | ``default``, ``utilization``, ``balanced``, and | | | | ``minimal``. | +---------------------------+---------+----------------------------------------------------+ | node-health-strategy | none | .. index:: | | | | pair: cluster option; node-health-strategy | | | | | | | | How the cluster should react to node health | | | | attributes (see :ref:`node-health`). Allowed values| | | | are ``none``, ``migrate-on-red``, ``only-green``, | | | | ``progressive``, and ``custom``. | +---------------------------+---------+----------------------------------------------------+ | node-health-base | 0 | .. index:: | | | | pair: cluster option; node-health-base | | | | | | | | The base health score assigned to a node. Only | | | | used when ``node-health-strategy`` is | | | | ``progressive``. | +---------------------------+---------+----------------------------------------------------+ | node-health-green | 0 | .. index:: | | | | pair: cluster option; node-health-green | | | | | | | | 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 | 0 | .. index:: | | | | pair: cluster option; node-health-yellow | | | | | | | | 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 | 0 | .. index:: | | | | pair: cluster option; node-health-red | | | | | | | | 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 | 15min | .. index:: | | | | pair: cluster option; cluster-recheck-interval | | | | | | | | Pacemaker is primarily event-driven, and looks | | | | ahead to know when to recheck the cluster for | | | | failure timeouts and most time-based rules | | | | *(since 2.0.3)*. However, it will also recheck the | | | | cluster after this amount of inactivity. This has | | | | two goals: rules with ``date_spec`` are only | | | | guaranteed to be checked this often, and it also | | | | serves as a fail-safe for some kinds of scheduler | | | | bugs. A value of 0 disables this polling; positive | | | | values are a time interval. | +---------------------------+---------+----------------------------------------------------+ | shutdown-lock | false | .. index:: | | | | pair: cluster option; shutdown-lock | | | | | | | | 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 | 0 | .. index:: | | | | pair: cluster option; shutdown-lock-limit | | | | | | | | 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)* | +---------------------------+---------+----------------------------------------------------+ | remove-after-stop | false | .. index:: | | | | pair: cluster option; remove-after-stop | | | | | | | | *Deprecated* Should the cluster remove | | | | resources from Pacemaker's executor after they are | | | | stopped? Values other than the default are, at | | | | best, poorly tested and potentially dangerous. | | | | This option is deprecated and will be removed in a | | | | future release. | +---------------------------+---------+----------------------------------------------------+ | startup-fencing | true | .. index:: | | | | pair: cluster option; startup-fencing | | | | | | | | *Advanced Use Only:* Should the cluster fence | | | | unseen nodes at start-up? Setting this to false is | | | | unsafe, because the unseen nodes could be active | | | | and running resources but unreachable. | +---------------------------+---------+----------------------------------------------------+ | election-timeout | 2min | .. index:: | | | | pair: cluster option; election-timeout | | | | | | | | *Advanced Use Only:* If you need to adjust this | | | | value, it probably indicates the presence of a bug.| +---------------------------+---------+----------------------------------------------------+ | shutdown-escalation | 20min | .. index:: | | | | pair: cluster option; shutdown-escalation | | | | | | | | *Advanced Use Only:* If you need to adjust this | | | | value, it probably indicates the presence of a bug.| +---------------------------+---------+----------------------------------------------------+ | join-integration-timeout | 3min | .. index:: | | | | pair: cluster option; join-integration-timeout | | | | | | | | *Advanced Use Only:* If you need to adjust this | | | | value, it probably indicates the presence of a bug.| +---------------------------+---------+----------------------------------------------------+ | join-finalization-timeout | 30min | .. index:: | | | | pair: cluster option; join-finalization-timeout | | | | | | | | *Advanced Use Only:* If you need to adjust this | | | | value, it probably indicates the presence of a bug.| +---------------------------+---------+----------------------------------------------------+ | transition-delay | 0s | .. index:: | | | | pair: cluster option; transition-delay | | | | | | | | *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/resources.rst b/doc/sphinx/Pacemaker_Explained/resources.rst index de511becff..a971c44c26 100644 --- a/doc/sphinx/Pacemaker_Explained/resources.rst +++ b/doc/sphinx/Pacemaker_Explained/resources.rst @@ -1,688 +1,696 @@ .. _resource: Cluster Resources ----------------- .. _s-resource-primitive: What is a Cluster Resource? ########################### .. 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 *class* specifying the standard that its resource agent follows, and a *type* identifying the specific service being managed. .. _s-resource-supported: .. index:: single: resource; class Resource Classes ################ Pacemaker supports several classes, or standards, of resource agents: * OCF * LSB * Systemd * Service * Fencing * Nagios *(deprecated since 2.1.6)* * Upstart *(deprecated since 2.1.0)* .. 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 classes. The number and purpose of parameters is left to the agent, which advertises them via the ``meta-data`` action. Unlike other classes, OCF agents have a *provider* as well as a class 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 services. Simply create a resource with ``systemd`` as the resource class 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 are various types of system services (``systemd``, ``upstart``, 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``, ``upstart``, and ``lsb``. In order, Pacemaker will try to find the named service as: * an LSB init script * a Systemd unit file * an Upstart job .. index:: single: Resource; STONITH single: STONITH; resources STONITH _______ The ``stonith`` class is used for managing fencing devices, discussed later in :ref:`fencing`. .. index:: single: Resource; Nagios Plugins single: Nagios Plugins; resources Nagios Plugins ______________ Nagios Plugins are a way to monitor services. Pacemaker can use these as resources, to react to a change in the service's status. To use plugins as resources, Pacemaker must have been built with support, and OCF-style meta-data for the plugins must be installed on nodes that can run them. Meta-data for several common plugins is provided by the `nagios-agents-metadata `_ project. The supported parameters for such a resource are same as the long options of the plugin. Start and monitor actions for plugin resources are implemented as invoking the plugin. A plugin result of "OK" (0) is treated as success, a result of "WARN" (1) is treated as a successful but degraded service, and any other result is considered a failure. A plugin resource is not going to change its status after recovery by restarting the plugin, so using them alone does not make sense with ``on-fail`` set (or left to default) to ``restart``. Another value could make sense, for example, if you want to fence or standby nodes that cannot reach some external service. A more common use case for plugin resources is to configure them with a ``container`` meta-attribute set to the name of another resource that actually makes the service available, such as a virtual machine or container. With ``container`` set, the plugin resource will automatically be colocated with the containing resource and ordered after it, and the containing resource will be considered failed if the plugin resource fails. This allows monitoring of a service inside a virtual machine or container, with recovery of the virtual machine or container if the service fails. .. warning:: Nagios support is deprecated in Pacemaker. Support will be dropped entirely at the next major release of Pacemaker. For monitoring a service inside a virtual machine or container, the recommended alternative is to configure the virtual machine as a guest node or the container as a :ref:`bundle `. For other use cases, or when the virtual machine or container image cannot be modified, the recommended alternative is to write a custom OCF agent for the service (which may even call the Nagios plugin as part of its status action). .. index:: single: Resource; Upstart single: Upstart; resources Upstart _______ Some Linux distributions previously used `Upstart `_ for system initialization and service management. Pacemaker is able to manage services using Upstart if the local system supports them and support was enabled when your Pacemaker software was built. The *jobs* that specify how services are managed are usually provided by the operating system distribution. .. important:: Make sure the host is *not* configured to start any Upstart services at boot that will be controlled by the cluster. .. warning:: Upstart support is deprecated in Pacemaker. Upstart is no longer actively maintained, and test platforms for it are no longer readily usable. Support will be dropped entirely at the next major release of Pacemaker. .. _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 +-------------+------------------------------------------------------------------+ | 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``, ``systemd``, | | | ``nagios`` *(deprecated since 2.1.6)*, and ``upstart`` | | | *(deprecated since 2.1.0)* | +-------------+------------------------------------------------------------------+ | description | .. index:: | | | single: description; resource | | | single: resource; property, description | | | | | | A description of the Resource Agent, intended for local use. | | | E.g. ``IP address for website`` | +-------------+------------------------------------------------------------------+ | 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, systemd or Upstart) resources is that they do not allow any 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. .. table:: **Meta-attributes of a Primitive Resource** :class: longtable :widths: 2 2 3 +----------------------------+----------------------------------+------------------------------------------------------+ | Field | Default | Description | +============================+==================================+======================================================+ | priority | 0 | .. index:: | | | | single: priority; resource option | | | | single: resource; option, priority | | | | | | | | If not all resources can be active, the cluster | | | | will stop lower priority resources in order to | | | | keep higher priority ones active. | +----------------------------+----------------------------------+------------------------------------------------------+ | critical | true | .. index:: | | | | single: critical; resource option | | | | single: resource; option, critical | | | | | | | | Use this value as the default for ``influence`` in | | | | all :ref:`colocation constraints | | | | ` involving this resource, | | | | as well as the implicit colocation constraints | - | | | created if this resource is in a :ref:`group | - | | | `. For details, see | + | | | created if this resource is in a | + | | | :ref:`group `. For details, see | | | | :ref:`s-coloc-influence`. *(since 2.1.0)* | +----------------------------+----------------------------------+------------------------------------------------------+ | target-role | Started | .. index:: | | | | single: target-role; resource option | | | | single: resource; option, target-role | | | | | | | | 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) | + | | | (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`` | +----------------------------+----------------------------------+------------------------------------------------------+ - | is-managed | TRUE | .. index:: | + | is-managed | TRUE | .. _is_managed: | + | | | | + | | | .. index:: | | | | single: is-managed; resource option | | | | single: resource; option, is-managed | | | | | - | | | Is the cluster allowed to start and stop | - | | | the resource? Allowed values: ``true``, ``false`` | + | | | If false, the cluster will not start or stop the | + | | | resource on any node. Recurring actions for the | + | | | resource are unaffected. Maintenance mode overrides | + | | | this setting. Allowed values: ``true``, ``false`` | +----------------------------+----------------------------------+------------------------------------------------------+ - | maintenance | FALSE | .. index:: | + | maintenance | FALSE | .. _rsc_maintenance: | + | | | | + | | | .. index:: | | | | single: maintenance; resource option | | | | single: resource; option, maintenance | | | | | - | | | Similar to the ``maintenance-mode`` | - | | | :ref:`cluster option `, but for | - | | | a single resource. If true, the resource will not | - | | | be started, stopped, or monitored on any node. This | - | | | differs from ``is-managed`` in that monitors will | - | | | not be run. Allowed values: ``true``, ``false`` | + | | | If true, the cluster will not start or stop 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 override this. Allowed values: | + | | | ``true``, ``false`` | +----------------------------+----------------------------------+------------------------------------------------------+ | resource-stickiness | 1 for individual clone | .. _resource-stickiness: | | | instances, 0 for all | | | | other resources | .. index:: | | | | single: resource-stickiness; resource option | | | | single: resource; option, resource-stickiness | | | | | | | | 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. | +----------------------------+----------------------------------+------------------------------------------------------+ | requires | ``quorum`` for resources | .. _requires: | | | with a ``class`` of ``stonith``, | | | | otherwise ``unfencing`` if | .. index:: | | | unfencing is active in the | single: requires; resource option | | | cluster, otherwise ``fencing`` | single: resource; option, requires | | | if ``stonith-enabled`` is true, | | | | otherwise ``quorum`` | Conditions under which the resource can be | | | | started. Allowed values: | | | | | | | | * ``nothing:`` can always be started | | | | * ``quorum:`` The cluster can only start this | | | | resource if a majority of the configured nodes | | | | are active | | | | * ``fencing:`` The cluster can only start this | | | | resource 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 ` | +----------------------------+----------------------------------+------------------------------------------------------+ | migration-threshold | INFINITY | .. index:: | | | | single: migration-threshold; resource option | | | | single: resource; option, migration-threshold | | | | | | | | 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 constrast, 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``. | +----------------------------+----------------------------------+------------------------------------------------------+ | failure-timeout | 0 | .. index:: | | | | single: failure-timeout; resource option | | | | single: resource; option, failure-timeout | | | | | | | | How many seconds to wait before acting as if the | | | | failure had not occurred, and potentially allowing | | | | the resource back to the node on which it failed. | | | | A value of 0 indicates that this feature is | | | | disabled. | +----------------------------+----------------------------------+------------------------------------------------------+ | multiple-active | stop_start | .. index:: | | | | single: multiple-active; resource option | | | | single: resource; option, multiple-active | | | | | | | | 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)* | +----------------------------+----------------------------------+------------------------------------------------------+ | allow-migrate | TRUE for ocf:pacemaker:remote | Whether the cluster should try to "live migrate" | | | resources, FALSE otherwise | this resource when it needs to be moved (see | | | | :ref:`live-migration`) | +----------------------------+----------------------------------+------------------------------------------------------+ | allow-unhealthy-nodes | 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)* | +----------------------------+----------------------------------+------------------------------------------------------+ | container-attribute-target | | Specific to bundle resources; see | | | | :ref:`s-bundle-attributes` | +----------------------------+----------------------------------+------------------------------------------------------+ | remote-node | | The name of the Pacemaker Remote guest node this | | | | resource is associated with, if any. If | | | | specified, this both enables the resource as a | | | | guest node and defines the unique name used to | | | | identify the guest node. The guest must be | | | | configured to run the Pacemaker Remote daemon | | | | when it is started. **WARNING:** This value | | | | cannot overlap with any resource or node IDs. | +----------------------------+----------------------------------+------------------------------------------------------+ | remote-port | 3121 | If ``remote-node`` is specified, the port on the | | | | guest used for its Pacemaker Remote connection. | | | | The Pacemaker Remote daemon on the guest must | | | | be configured to listen on this port. | +----------------------------+----------------------------------+------------------------------------------------------+ | remote-addr | value of ``remote-node`` | If ``remote-node`` is specified, the IP | | | | address or hostname used to connect to the | | | | guest via Pacemaker Remote. The Pacemaker Remote | | | | daemon on the guest must be configured to accept | | | | connections on this address. | +----------------------------+----------------------------------+------------------------------------------------------+ | remote-connect-timeout | 60s | If ``remote-node`` is specified, how long before | | | | a pending guest connection will time out. | +----------------------------+----------------------------------+------------------------------------------------------+ 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 classes (lsb, systemd and upstart *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