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diff --git a/doc/sphinx/Pacemaker_Explained/acls.rst b/doc/sphinx/Pacemaker_Explained/acls.rst
index 1786768a76..7385f97e70 100644
--- a/doc/sphinx/Pacemaker_Explained/acls.rst
+++ b/doc/sphinx/Pacemaker_Explained/acls.rst
@@ -1,335 +1,337 @@
+.. _acl:
+
Access Control Lists (ACLs)
---------------------------
.. Convert_to_RST:
anchor:ch-acls[Chapter 13, ACLs]
indexterm:[access control list]
indexterm:[ACL]
By default, the +root+ user or any user in the +haclient+ group can modify
Pacemaker's CIB without restriction. Pacemaker offers 'access control lists
(ACLs)' to provide more fine-grained authorization.
== ACL Prerequisites ==
In order to use ACLs:
* The Pacemaker software must have been compiled with ACL support. If the
output of the command `pacemakerd --features` contains `acls`, your
installation supports ACLs.
* Desired users must have user accounts in the +haclient+ group on all nodes in
the cluster.
* If your CIB was created before Pacemaker 1.1.12, it may need to be updated to
the current schema using `cibadmin --upgrade` in order to use the syntax
documented here.
* The +enable-acl+ <<s-cluster-options,cluster option>> must be set to true.
== ACL Configuration ==
ACLs are specified within an +acls+ element of the CIB. The +acls+ element may
contain any number of +acl_role+, +acl_target+, and +acl_group+ elements.
== ACL Roles ==
An ACL role is a collection of permissions allowing or denying access to
particular portions of the CIB.
.Properties of an ACL Role
[width="95%",cols="1m,<3",options="header",align="center"]
|====
|Attribute
|Description
|id
|A unique name for the role (required)
indexterm:[id,acl_role]
indexterm:[access control list,acl_role,id]
|description
|Arbitrary text (not used by Pacemaker)
indexterm:[description,acl_role]
indexterm:[access control list,acl_role,description]
|====
An +acl_role+ element may contain any number of +acl_permission+ elements.
.Properties of an ACL Permission
[width="95%",cols="1m,<3",options="header",align="center"]
|====
|Attribute
|Description
|id
|A unique name for the permission (required)
indexterm:[id,acl_permission]
indexterm:[access control list,acl_permission,id]
|description
|Arbitrary text (not used by Pacemaker)
indexterm:[description,acl_permission]
indexterm:[access control list,acl_permission,description]
|kind
|The access being granted. Allowed values are +read+, +write+, and +deny+.
A value of +write+ grants both read and write access.
indexterm:[kind,acl_permission]
indexterm:[access control list,acl_permission,kind]
|object-type
|The name of an XML element in the CIB to which the permission applies.
(Exactly one of +object-type+, +xpath+, and +reference+ must be specified for
a permission.)
indexterm:[object-type,acl_permission]
indexterm:[access control list,acl_permission,object-type]
|attribute
|If specified, the permission applies only to +object-type+ elements that have
this attribute set (to any value). If not specified, the permission applies to
all +object-type+ elements. May only be used with +object-type+.
indexterm:[attribute,acl_permission]
indexterm:[access control list,acl_permission,attribute]
|reference
|The ID of an XML element in the CIB to which the permission applies.
(Exactly one of +object-type+, +xpath+, and +reference+ must be specified for
a permission.)
indexterm:[reference,acl_permission]
indexterm:[access control list,acl_permission,reference]
|xpath
|An https://www.w3.org/TR/xpath-10/[XPath] specification selecting an XML
element in the CIB to which the permission applies. Attributes may be
specified in the XPath to select particular elements, but the permissions
apply to the entire element.
(Exactly one of +object-type+, +xpath+, and +reference+ must be specified for
a permission.)
indexterm:[xpath,acl_permission]
indexterm:[access control list,acl_permission,xpath]
|====
[IMPORTANT]
====
* Permissions are applied to the selected XML element's entire XML subtree
(all elements enclosed within it).
* Write permission grants the ability to create, modify, or remove the element
and its subtree, and also the ability to create any "scaffolding" elements
(enclosing elements that do not have attributes other than an ID).
* Permissions for more specific matches (more deeply nested elements) take
precedence over more general ones.
* If multiple permissions are configured for the same match (for example, in
different roles applied to the same user), any +deny+ permission takes
precedence, then +write+, then lastly +read+.
====
== ACL Targets and Groups ==
ACL targets correspond to user accounts on the system.
.Properties of an ACL Target
[width="95%",cols="1m,<3",options="header",align="center"]
|====
|Attribute
|Description
|id
|The name of a user on the system (required)
indexterm:[id,acl_target]
indexterm:[access control list,acl_target,id]
|====
ACL groups may be specified, but are not currently used by Pacemaker. This is
expected to change in a future version.
.Properties of an ACL Group
[width="95%",cols="1m,<3",options="header",align="center"]
|====
|Attribute
|Description
|id
|The name of a group on the system (required)
indexterm:[id,acl_group]
indexterm:[access control list,acl_group,id]
|====
Each +acl_target+ and +acl_group+ element may contain any number of +role+
elements.
.Properties of an ACL Role Reference
[width="95%",cols="1m,<3",options="header",align="center"]
|====
|Attribute
|Description
|id
|The +id+ of an +acl_role+ element that specifies permissions granted to the
enclosing target or group
indexterm:[id,role]
indexterm:[access control list,role,id]
|====
[IMPORTANT]
====
The +root+ and +hacluster+ user accounts always have full access to the CIB,
regardless of ACLs. For other user accounts, when +enable-acl+ is true,
permission to all parts of the CIB is denied by default (permissions must be
explicitly granted).
====
== ACL Examples ==
[source,XML]
----
<acls>
<acl_role id="read_all">
<acl_permission id="read_all-cib" kind="read" xpath="/cib" />
</acl_role>
<acl_role id="operator">
<acl_permission id="operator-maintenance-mode" kind="write"
xpath="//crm_config//nvpair[@name='maintenance-mode']" />
<acl_permission id="operator-maintenance-attr" kind="write"
xpath="//nvpair[@name='maintenance']" />
<acl_permission id="operator-target-role" kind="write"
xpath="//resources//meta_attributes/nvpair[@name='target-role']" />
<acl_permission id="operator-is-managed" kind="write"
xpath="//resources//nvpair[@name='is-managed']" />
<acl_permission id="operator-rsc_location" kind="write"
object-type="rsc_location" />
</acl_role>
<acl_role id="administrator">
<acl_permission id="administrator-cib" kind="write" xpath="/cib" />
</acl_role>
<acl_role id="minimal">
<acl_permission id="minimal-standby" kind="read"
description="allow reading standby node attribute (permanent or transient)"
xpath="//instance_attributes/nvpair[@name='standby']"/>
<acl_permission id="minimal-maintenance" kind="read"
description="allow reading maintenance node attribute (permanent or transient)"
xpath="//nvpair[@name='maintenance']"/>
<acl_permission id="minimal-target-role" kind="read"
description="allow reading resource target roles"
xpath="//resources//meta_attributes/nvpair[@name='target-role']"/>
<acl_permission id="minimal-is-managed" kind="read"
description="allow reading resource managed status"
xpath="//resources//meta_attributes/nvpair[@name='is-managed']"/>
<acl_permission id="minimal-deny-instance-attributes" kind="deny"
xpath="//instance_attributes"/>
<acl_permission id="minimal-deny-meta-attributes" kind="deny"
xpath="//meta_attributes"/>
<acl_permission id="minimal-deny-operations" kind="deny"
xpath="//operations"/>
<acl_permission id="minimal-deny-utilization" kind="deny"
xpath="//utilization"/>
<acl_permission id="minimal-nodes" kind="read"
description="allow reading node names/IDs (attributes are denied separately)"
xpath="/cib/configuration/nodes"/>
<acl_permission id="minimal-resources" kind="read"
description="allow reading resource names/agents (parameters are denied separately)"
xpath="/cib/configuration/resources"/>
<acl_permission id="minimal-deny-constraints" kind="deny"
xpath="/cib/configuration/constraints"/>
<acl_permission id="minimal-deny-topology" kind="deny"
xpath="/cib/configuration/fencing-topology"/>
<acl_permission id="minimal-deny-op_defaults" kind="deny"
xpath="/cib/configuration/op_defaults"/>
<acl_permission id="minimal-deny-rsc_defaults" kind="deny"
xpath="/cib/configuration/rsc_defaults"/>
<acl_permission id="minimal-deny-alerts" kind="deny"
xpath="/cib/configuration/alerts"/>
<acl_permission id="minimal-deny-acls" kind="deny"
xpath="/cib/configuration/acls"/>
<acl_permission id="minimal-cib" kind="read"
description="allow reading cib element and crm_config/status sections"
xpath="/cib"/>
</acl_role>
<acl_target id="alice">
<role id="minimal"/>
</acl_target>
<acl_target id="bob">
<role id="read_all"/>
</acl_target>
<acl_target id="carol">
<role id="read_all"/>
<role id="operator"/>
</acl_target>
<acl_target id="dave">
<role id="administrator"/>
</acl_target>
</acls>
----
In the above example, the user +alice+ has the minimal permissions necessary to
run basic Pacemaker CLI tools, including using `crm_mon` to view the cluster
status, without being able to modify anything. The user +bob+ can view the
entire configuration and status of the cluster, but not make any changes. The
user +carol+ can read everything, and change selected cluster properties as
well as resource roles and location constraints. Finally, +dave+ has full read
and write access to the entire CIB.
Looking at the +minimal+ role in more depth, it is designed to allow read
access to the +cib+ tag itself, while denying access to particular portions of
its subtree (which is the entire CIB).
This is because the DC node is indicated in the +cib+ tag, so `crm_mon` will
not be able to report the DC otherwise. However, this does change the security
model to allow by default, since any portions of the CIB not explicitly denied
will be readable. The +cib+ read access could be removed and replaced with read
access to just the +crm_config+ and +status+ sections, for a safer approach at
the cost of not seeing the DC in status output.
For a simpler configuration, the +minimal+ role allows read access to the
entire +crm_config+ section, which contains cluster properties. It would be
possible to allow read access to specific properties instead (such as
+stonith-enabled+, +dc-uuid+, +have-quorum+, and +cluster-name+) to restrict
access further while still allowing status output, but cluster properties are
unlikely to be considered sensitive.
diff --git a/doc/sphinx/Pacemaker_Explained/advanced-options.rst b/doc/sphinx/Pacemaker_Explained/advanced-options.rst
index 5ee5c9b5ed..ec064b33af 100644
--- a/doc/sphinx/Pacemaker_Explained/advanced-options.rst
+++ b/doc/sphinx/Pacemaker_Explained/advanced-options.rst
@@ -1,759 +1,776 @@
Advanced Configuration
----------------------
.. Convert_to_RST:
[[s-recurring-start]]
== Specifying When Recurring Actions are Performed ==
By default, recurring actions are scheduled relative to when the
resource started. So if your resource was last started at 14:32 and
you have a backup set to be performed every 24 hours, then the backup
will always run in the middle of the business day -- hardly
desirable.
To specify a date and time that the operation should be relative to, set
the operation's +interval-origin+. The cluster uses this point to
calculate the correct +start-delay+ such that the operation will occur
at _origin + (interval * N)_.
So, if the 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 with a start delay of 11 hours and 28 minutes. If the
resource is moved to another node before 2am, then the operation is
cancelled.
The value specified for +interval+ and +interval-origin+ can be any
date/time conforming to the
http://en.wikipedia.org/wiki/ISO_8601[ISO8601 standard]. By way of
example, to specify an operation that would run on the first Monday of
2009 and every Monday after that, you would add:
.Specifying a Base for Recurring Action Intervals
=====
[source,XML]
<op id="my-weekly-action" name="custom-action" interval="P7D" interval-origin="2009-W01-1"/>
=====
-
- [[s-failure-handling]]
- == Handling Resource Failure ==
+
+
+.. _failure-handling:
+
+Handling Resource Failure
+#########################
+
+
+.. Convert_to_RST_2:
By default, Pacemaker will attempt to recover failed resources by restarting
them. However, failure recovery is highly configurable.
=== 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:
----
# 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:
----
# 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).
=== 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.
footnote:[
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.
]
If you define +migration-threshold=pass:[<replaceable>N</replaceable>]+ for a
resource, it will be banned from the original node after 'N' failures.
[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
falure timeout.
====
For example, a setting of +migration-threshold=2+ and +failure-timeout=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 concept:
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 STONITH is enabled, then the cluster will fence the node
in order to be able to start the resource elsewhere. If STONITH is
not enabled, 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
the failure timeout.
== Moving Resources ==
indexterm:[Moving,Resources]
indexterm:[Resource,Moving]
=== 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.
==== 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, one 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:
----
# 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:
----
# crm_standby -G --node sles-2
----
To change the current node's standby status, use `-v` instead of `-G`:
----
# 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:
----
# crm_resource -M -r Email -H sles-2
----
Behind the scenes, the tool will create the following location constraint:
[source,XML]
<rsc_location rsc="Email" node="sles-2" score="INFINITY"/>
It is important to note that subsequent invocations of `crm_resource
-M` are not cumulative. So, if you ran these commands
----
# 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:
----
# 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+, 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`:
----
# 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:
----
# crm_resource -B -r Email
----
Which will instead create a negative constraint, like
[source,XML]
<rsc_location rsc="Email" node="sles-1" score="-INFINITY"/>
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 <<node-score-equal>>. The tool can detect
some of these cases and deals with them by creating both
positive and negative constraints. E.g.
+Email+ prefers +sles-1+ with a score of +-INFINITY+
+Email+ prefers +sles-2+ with a score of +INFINITY+
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.
==== 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
list of machines (specified by DNS hostname or IPv4/IPv6 address) are
reachable and uses the results to maintain a node attribute called +pingd+
by default.
footnote:[
The attribute name is customizable, in order to allow multiple ping groups to be defined.
]
[NOTE]
===========
Older versions of Pacemaker used a different agent *ocf:pacemaker:pingd* which
is now deprecated in favor of *ping*. If your version of Pacemaker does not
contain the *ping* resource agent, download the latest version from
https://github.com/ClusterLabs/pacemaker/tree/master/extra/resources/ping
===========
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.
.Common Options for a 'ping' Resource
[width="95%",cols="1m,<4",options="header",align="center"]
|=========================================================
|Field
|Description
|dampen
|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.
indexterm:[dampen,Ping Resource Option]
indexterm:[Ping Resource,Option,dampen]
|multiplier
|The number of connected ping nodes gets multiplied by this value to
get a score. Useful when there are multiple ping nodes configured.
indexterm:[multiplier,Ping Resource Option]
indexterm:[Ping Resource,Option,multiplier]
|host_list
|The machines to contact in order to determine the current
connectivity status. Allowed values include resolvable DNS host
names, IPv4 and IPv6 addresses.
indexterm:[host_list,Ping Resource Option]
indexterm:[Ping Resource,Option,host_list]
|=========================================================
.An example ping cluster resource that checks node connectivity once every minute
=====
[source,XML]
------------
<clone id="Connected">
<primitive id="ping" provider="pacemaker" class="ocf" type="ping">
<instance_attributes id="ping-attrs">
<nvpair id="pingd-dampen" name="dampen" value="5s"/>
<nvpair id="pingd-multiplier" name="multiplier" value="1000"/>
<nvpair id="pingd-hosts" name="host_list" value="my.gateway.com www.bigcorp.com"/>
</instance_attributes>
<operations>
<op id="ping-monitor-60s" interval="60s" name="monitor"/>
</operations>
</primitive>
</clone>
------------
=====
[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
<<ch-rules>>.
======
There are a number of ways to use the connectivity data.
The most common setup is for people to have a single ping
target (e.g. the service network's default gateway), to prevent the cluster
from running a resource on any unconnected node.
.Don't run a resource on unconnected nodes
=====
[source,XML]
-------
<rsc_location id="WebServer-no-connectivity" rsc="Webserver">
<rule id="ping-exclude-rule" score="-INFINITY" >
<expression id="ping-exclude" attribute="pingd" operation="not_defined"/>
</rule>
</rsc_location>
-------
=====
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.
.Run only on nodes connected to three or more ping targets.
=====
[source,XML]
-------
<primitive id="ping" provider="pacemaker" class="ocf" type="ping">
... <!-- omitting some configuration to highlight important parts -->
<nvpair id="pingd-multiplier" name="multiplier" value="1000"/>
...
</primitive>
...
<rsc_location id="WebServer-connectivity" rsc="Webserver">
<rule id="ping-prefer-rule" score="-INFINITY" >
<expression id="ping-prefer" attribute="pingd" operation="lt" value="3000"/>
</rule>
</rsc_location>
-------
=====
Alternatively, you can tell the cluster only to _prefer_ nodes with the best
connectivity. Just be sure to set +multiplier+ to a value higher than
that of +resource-stickiness+ (and don't set either of them to
+INFINITY+).
.Prefer the node with the most connected ping nodes
=====
[source,XML]
-------
<rsc_location id="WebServer-connectivity" rsc="Webserver">
<rule id="ping-prefer-rule" score-attribute="pingd" >
<expression id="ping-prefer" attribute="pingd" operation="defined"/>
</rule>
</rsc_location>
-------
=====
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:
.How the cluster translates the above location constraint
=====
[source,XML]
-------
<rsc_location id="ping-1" rsc="Webserver" node="sles-1" score="5000"/>
<rsc_location id="ping-2" rsc="Webserver" node="sles-2" score="2000"/>
-------
=====
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).
.A more complex example of choosing a location based on connectivity
=====
[source,XML]
-------
<rsc_location id="WebServer-connectivity" rsc="Webserver">
<rule id="ping-exclude-rule" score="-INFINITY" >
<expression id="ping-exclude" attribute="pingd" operation="lt" value="3000"/>
</rule>
<rule id="ping-prefer-rule" score-attribute="pingd" >
<expression id="ping-prefer" attribute="pingd" operation="defined"/>
</rule>
</rsc_location>
-------
=====
-
- [[s-migrating-resources]]
- === Migrating Resources ===
+
+
+.. _live-migration:
+
+Migrating Resources
+___________________
+
+
+.. Convert_to_RST_3:
Normally, when the cluster needs to move a resource, it fully restarts
the resource (i.e. stops the resource on the current node
and starts it on the new node).
However, some types of resources, such as Xen virtual guests, 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 Migration Checklist
below, and 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
* The resource may not be a clone.
* The resource must use an OCF style agent.
* 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 metadata.
* 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.
+
+
+.. _node-health:
+
+Tracking Node Health
+####################
- [[s-node-health]]
- == Tracking Node Health ==
+.. Convert_to_RST_4:
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.
=== 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:
.Allowed Values for Node Health Attributes
[width="95%",cols="1,<3",options="header",align="center"]
|=========================================================
|Value
|Intended significance
|+red+
|This indicator is unhealthy
indexterm:[Node health,red]
|+yellow+
|This indicator is becoming unhealthy
indexterm:[Node health,yellow]
|+green+
|This indicator is healthy
indexterm:[Node health,green]
|'integer'
|A numeric score to apply to all resources on this node
(0 or positive is healthy, negative is unhealthy)
indexterm:[Node health,score]
|=========================================================
=== 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:
.Node Health Strategies
[width="95%",cols="1m,<3",options="header",align="center"]
|=========================================================
|Value
|Effect
|none
|Do not track node health attributes at all.
indexterm:[Node health,none]
|migrate-on-red
|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+.
indexterm:[Node health,migrate-on-red]
|only-green
|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+.
indexterm:[Node health,only-green]
|progressive
|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.
indexterm:[Node health,progressive]
|custom
|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 rules
(see <<ch-rules>>) referencing node health attributes.
indexterm:[Node health,custom]
|=========================================================
=== Measuring Node Health ===
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 ways are resource agents or separate daemons.
Pacemaker provides examples that can be used directly or as a basis for
custom code. The +ocf:pacemaker:HealthCPU+ and +ocf:pacemaker:HealthSMART+
resource agents set node health attributes based on CPU and disk parameters.
The +ipmiservicelogd+ daemon sets node health attributes based on IPMI
values (the +ocf:pacemaker:SystemHealth+ resource agent can be used to manage
the daemon as a cluster resource).
In order to take advantage of this feature - firstly add the resource to your cluster, preferably as a cloned resource to constantly measure health on all nodes:
=====
[source,XML]
------------
<clone id="resHealthIOWait-clone">
<primitive class="ocf" id="HealthIOWait" provider="pacemaker" type="HealthIOWait">
<instance_attributes id="resHealthIOWait-instance_attributes">
<nvpair id="resHealthIOWait-instance_attributes-red_limit" name="red_limit" value="30"/>
<nvpair id="resHealthIOWait-instance_attributes-yellow_limit" name="yellow_limit" value="10"/>
</instance_attributes>
<operations>
<op id="resHealthIOWait-monitor-interval-5" interval="5" name="monitor" timeout="5"/>
<op id="resHealthIOWait-start-interval-0s" interval="0s" name="start" timeout="10s"/>
<op id="resHealthIOWait-stop-interval-0s" interval="0s" name="stop" timeout="10s"/>
</operations>
</primitive>
</clone>
------------
=====
This way attrd_updater will set proper status for each node running this resource. Any attribute matching "#health-[a-zA-z]+" will force cluster to migrate all resources from unhealthy node and place it on other nodes according to all constraints defined in your cluster.
When the node is no longer faulty you can force the cluster to restart the cloned resource on faulty node and make it available to take resources, in this case since we are using HealthIOWait provider:
----
# attrd_updater -n "#health-iowait" -U "green" --node="<nodename>" -d "60s"
----
== Reloading Services After a Definition Change ==
The cluster automatically detects changes to the definition of
services it manages. The normal response is to stop the
service (using the old definition) and start it again (with the new
definition). This works well, but some services 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:
. Accept the +reload+ operation and perform any required actions.
_The actions here depend completely on your application!_
+
.The DRBD agent's logic for supporting +reload+
=====
[source,Bash]
-------
case $1 in
start)
drbd_start
;;
stop)
drbd_stop
;;
reload)
drbd_reload
;;
monitor)
drbd_monitor
;;
*)
drbd_usage
exit $OCF_ERR_UNIMPLEMENTED
;;
esac
exit $?
-------
=====
. Advertise the +reload+ operation in the +actions+ section of its metadata
+
.The DRBD Agent Advertising Support for the +reload+ Operation
=====
[source,XML]
-------
<?xml version="1.0"?>
<!DOCTYPE resource-agent SYSTEM "ra-api-1.dtd">
<resource-agent name="drbd">
<version>1.1</version>
<longdesc lang="en">
Master/Slave OCF Resource Agent for DRBD
</longdesc>
...
<actions>
<action name="start" timeout="240" />
<action name="reload" timeout="240" />
<action name="promote" timeout="90" />
<action name="demote" timeout="90" />
<action name="notify" timeout="90" />
<action name="stop" timeout="100" />
<action name="meta-data" timeout="5" />
<action name="validate-all" timeout="30" />
</actions>
</resource-agent>
-------
=====
. Advertise one or more parameters that can take effect using +reload+.
+
Any parameter with the +unique+ set to 0 is eligible to be used in this way.
+
.Parameter that can be changed using reload
=====
[source,XML]
-------
<parameter name="drbdconf" unique="0">
<longdesc lang="en">Full path to the drbd.conf file.</longdesc>
<shortdesc lang="en">Path to drbd.conf</shortdesc>
<content type="string" default="${OCF_RESKEY_drbdconf_default}"/>
</parameter>
-------
=====
Once these requirements are satisfied, the cluster will automatically
know to reload the resource (instead of restarting) when a non-unique
field changes.
[NOTE]
======
Metadata will not be re-read unless the resource needs to be started. This may
mean that the resource will be restarted the first time, even though you
changed a parameter with +unique=0+.
======
[NOTE]
======
If both a unique and non-unique field are changed simultaneously, the
resource will still be restarted.
======
diff --git a/doc/sphinx/Pacemaker_Explained/resources.rst b/doc/sphinx/Pacemaker_Explained/resources.rst
index 6e24844550..592e299121 100644
--- a/doc/sphinx/Pacemaker_Explained/resources.rst
+++ b/doc/sphinx/Pacemaker_Explained/resources.rst
@@ -1,964 +1,980 @@
+.. _resource:
+
Cluster Resources
-----------------
.. Convert_to_RST:
[[s-resource-primitive]]
== What is a Cluster Resource? ==
indexterm:[Resource]
A resource is a service made highly available by a cluster.
The simplest type of resource, a 'primitive' resource, is described
in this chapter. More complex forms, such as groups and clones,
are described in later chapters.
Every primitive resource has a 'resource agent'. A resource agent is an
external program that abstracts the service it provides and present a
consistent view to the cluster.
This allows the cluster to be agnostic about the resources it manages.
The cluster doesn't need to understand how the resource works because
it relies on the resource agent to do the right thing when given a
`start`, `stop` or `monitor` command. For this reason, it is crucial that
resource agents are well-tested.
Typically, resource agents come in the form of shell scripts. However,
they can be written using any technology (such as C, Python or Perl)
that the author is comfortable with.
[[s-resource-supported]]
== Resource Classes ==
indexterm:[Resource,class]
Pacemaker supports several classes of agents:
* OCF
* LSB
* Upstart
* Systemd
* Service
* Fencing
* Nagios Plugins
=== Open Cluster Framework ===
indexterm:[Resource,OCF]
indexterm:[OCF,Resources]
indexterm:[Open Cluster Framework,Resources]
The OCF standard
footnote:[See https://github.com/ClusterLabs/OCF-spec/tree/master/ra . The
Pacemaker implementation has been somewhat extended from the OCF specs.]
is basically an extension of the Linux Standard Base conventions for
init scripts to:
* support parameters,
* make them self-describing, and
* make them extensible
OCF specs have strict definitions of the exit codes that actions must return.
footnote:[
The resource-agents source code includes the `ocf-tester` script, which
can be useful in this regard.
]
The cluster follows these specifications exactly, and giving the wrong
exit code will cause the cluster to behave in ways you will likely
find puzzling and annoying. In particular, the cluster needs to
distinguish a completely stopped resource from one which is in some
erroneous and indeterminate state.
Parameters are passed to the resource agent as environment variables, with the
special prefix +OCF_RESKEY_+. So, a parameter which the user thinks
of as +ip+ will be passed to the resource agent as +OCF_RESKEY_ip+. The
number and purpose of the parameters is left to the resource agent; however,
the resource agent should use the `meta-data` command to advertise any that it
supports.
The OCF class is the most preferred as it is an industry standard,
highly flexible (allowing parameters to be passed to agents in a
non-positional manner) and self-describing.
For more information, see the
http://www.linux-ha.org/wiki/OCF_Resource_Agents[reference] and
the 'Resource Agents' chapter of 'Pacemaker Administration'.
=== Linux Standard Base ===
indexterm:[Resource,LSB]
indexterm:[LSB,Resources]
indexterm:[Linux Standard Base,Resources]
'LSB' resource agents are more commonly known as 'init scripts'. If a full path
is not given, they are assumed to be located in +/etc/init.d+.
Commonly, they are provided by the OS distribution. In order to be used
with a Pacemaker cluster, they must conform to the LSB specification.
footnote:[
See
http://refspecs.linux-foundation.org/LSB_3.0.0/LSB-Core-generic/LSB-Core-generic/iniscrptact.html
for the LSB Spec as it relates to init scripts.
]
[WARNING]
====
Many distributions or particular software packages claim LSB compliance
but ship with broken init scripts. For details on how to check whether
your init script is LSB-compatible, see the 'Resource Agents' chapter of
'Pacemaker Administration'. Common problematic violations of the LSB
standard include:
* Not implementing the +status+ operation at all
* Not observing the correct exit status codes for
+start+/+stop+/+status+ actions
* Starting a started resource returns an error
* Stopping a stopped resource returns an error
====
[IMPORTANT]
====
Remember to make sure the computer is _not_ configured to start any
services at boot time -- that should be controlled by the cluster.
====
[[s-resource-supported-systemd]]
=== Systemd ===
indexterm:[Resource,Systemd]
indexterm:[Systemd,Resources]
Some newer distributions have replaced the old
http://en.wikipedia.org/wiki/Init#SysV-style["SysV"] style of
initialization daemons and scripts with an alternative called
http://www.freedesktop.org/wiki/Software/systemd[Systemd].
Pacemaker is able to manage these services _if they are present_.
Instead of init scripts, systemd has 'unit files'. Generally, the
services (unit files) are provided by the OS distribution, but there
are online guides for converting from init scripts.
footnote:[For example,
http://0pointer.de/blog/projects/systemd-for-admins-3.html]
[IMPORTANT]
====
Remember to make sure the computer is _not_ configured to start any
services at boot time -- that should be controlled by the cluster.
====
=== Upstart ===
indexterm:[Resource,Upstart]
indexterm:[Upstart,Resources]
Some newer distributions have replaced the old
http://en.wikipedia.org/wiki/Init#SysV-style["SysV"] style of
initialization daemons (and scripts) with an alternative called
http://upstart.ubuntu.com/[Upstart].
Pacemaker is able to manage these services _if they are present_.
Instead of init scripts, upstart has 'jobs'. Generally, the
services (jobs) are provided by the OS distribution.
[IMPORTANT]
====
Remember to make sure the computer is _not_ configured to start any
services at boot time -- that should be controlled by the cluster.
====
=== System Services ===
indexterm:[Resource,System Services]
indexterm:[System Service,Resources]
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
=== STONITH ===
indexterm:[Resource,STONITH]
indexterm:[STONITH,Resources]
The STONITH class is used exclusively for fencing-related resources. This is
discussed later in <<ch-fencing>>.
=== Nagios Plugins ===
indexterm:[Resource,Nagios Plugins]
indexterm:[Nagios Plugins,Resources]
Nagios Plugins
footnote:[The project has two independent forks, hosted at
https://www.nagios-plugins.org/ and https://www.monitoring-plugins.org/. Output
from both projects' plugins is similar, so plugins from either project can be
used with pacemaker.]
allow us to monitor services on remote hosts.
Pacemaker is able to do remote monitoring with the plugins _if they are
present_.
A common use case is to configure them as resources belonging to a resource
container (usually a virtual machine), and the container will be restarted
if any of them has failed. Another use is to configure them as ordinary
resources to be used for monitoring hosts or services via the network.
The supported parameters are same as the long options of the plugin.
[[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.
.Properties of a Primitive Resource
[width="95%",cols="1m,<6",options="header",align="center"]
|=========================================================
|Field
|Description
|id
|Your name for the resource
indexterm:[id,Resource]
indexterm:[Resource,Property,id]
|class
|The standard the resource agent conforms to. Allowed values:
+lsb+, +nagios+, +ocf+, +service+, +stonith+, +systemd+, +upstart+
indexterm:[class,Resource]
indexterm:[Resource,Property,class]
|type
|The name of the Resource Agent you wish to use. E.g. +IPaddr+ or +Filesystem+
indexterm:[type,Resource]
indexterm:[Resource,Property,type]
|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.
indexterm:[provider,Resource]
indexterm:[Resource,Property,provider]
|=========================================================
The XML definition of a resource can be queried with the `crm_resource` tool.
For example:
----
# crm_resource --resource Email --query-xml
----
might produce:
.A system resource definition
=====
[source,XML]
<primitive id="Email" class="service" type="exim"/>
=====
[NOTE]
=====
One of the main drawbacks to system services (LSB, systemd or
Upstart) resources is that they do not allow any parameters!
=====
////
See https://tools.ietf.org/html/rfc5737 for choice of example IP address
////
.An OCF resource definition
=====
[source,XML]
-------
<primitive id="Public-IP" class="ocf" type="IPaddr" provider="heartbeat">
<instance_attributes id="Public-IP-params">
<nvpair id="Public-IP-ip" name="ip" value="192.0.2.2"/>
</instance_attributes>
</primitive>
-------
=====
.. _resource_options:
Resource Options
################
.. Convert_to_RST_2:
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.
.Meta-attributes of a Primitive Resource
[width="95%",cols="2m,2,<5",options="header",align="center"]
|=========================================================
|Field
|Default
|Description
|priority
|0
|If not all resources can be active, the cluster will stop lower
priority resources in order to keep higher priority ones active.
indexterm:[priority,Resource Option]
indexterm:[Resource,Option,priority]
|target-role
|Started
a|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
<<s-resource-promotable,promotable clone resources>>, promoted to master if
appropriate)
* +Slave:+ Allow the resource to be started, but only in Slave mode if
the resource is <<s-resource-promotable,promotable>>
* +Master:+ Equivalent to +Started+
indexterm:[target-role,Resource Option]
indexterm:[Resource,Option,target-role]
|is-managed
|TRUE
|Is the cluster allowed to start and stop the resource? Allowed
values: +true+, +false+
indexterm:[is-managed,Resource Option]
indexterm:[Resource,Option,is-managed]
|maintenance
|FALSE
|Similar to the +maintenance-mode+ <<s-cluster-options,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+
indexterm:[maintenance,Resource Option]
indexterm:[Resource,Option,maintenance]
.. _resource-stickiness:
placeholder
.. Convert_to_RST_3:
|resource-stickiness
|1 for individual clone instances, 0 for all other resources
|A score that will be added to the current node when a resource is already
active. This allows running resources to stay where they are, even if
they would be placed elsewhere if they were being started from a stopped
state.
indexterm:[resource-stickiness,Resource Option]
indexterm:[Resource,Option,resource-stickiness]
-
+
+
+.. _requires:
+
+ placeholder
+
+.. Convert_to_RST_4:
+
|requires
|+quorum+ for resources with a +class+ of +stonith+,
otherwise +unfencing+ if unfencing is active in the cluster,
otherwise +fencing+ if +stonith-enabled+ is true, otherwise +quorum+
a|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 <<ch-fencing,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
<<s-unfencing,unfenced>>
indexterm:[requires,Resource Option]
indexterm:[Resource,Option,requires]
|migration-threshold
|INFINITY
|How many failures may occur for this resource on a node, before this
node is marked ineligible to host this resource. A value of 0 indicates that
this feature is disabled (the node will never be marked ineligible); by
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+.
indexterm:[migration-threshold,Resource Option]
indexterm:[Resource,Option,migration-threshold]
|failure-timeout
|0
|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.
indexterm:[failure-timeout,Resource Option]
indexterm:[Resource,Option,failure-timeout]
|multiple-active
|stop_start
a|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
indexterm:[multiple-active,Resource Option]
indexterm:[Resource,Option,multiple-active]
|allow-migrate
|TRUE for ocf:pacemaker:remote resources, FALSE otherwise
|Whether the cluster should try to "live migrate" this resource when it needs
to be moved (see <<s-migrating-resources>>)
|container-attribute-target
|
|Specific to bundle resources; see <<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:
-------
# 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:
.An LSB resource with cluster options
=====
[source,XML]
-------
<primitive id="Email" class="lsb" type="exim">
<meta_attributes id="Email-meta_attributes">
<nvpair id="Email-meta_attributes-priority" name="priority" value="100"/>
<nvpair id="Email-meta_attributes-multiple-active" name="multiple-active" value="block"/>
</meta_attributes>
</primitive>
-------
=====
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 <<ch-rules,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,
----
# 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,
----
# crm_resource --resource Public-IP --set-parameter ip --parameter-value 192.0.2.2
----
would create an entry in the resource like this:
.An example OCF resource with instance attributes
=====
[source,XML]
-------
<primitive id="Public-IP" class="ocf" type="IPaddr" provider="heartbeat">
<instance_attributes id="params-public-ip">
<nvpair id="public-ip-addr" name="ip" value="192.0.2.2"/>
</instance_attributes>
</primitive>
-------
=====
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.
.Displaying the metadata for the Dummy resource agent template
=====
----
# export OCF_ROOT=/usr/lib/ocf
# $OCF_ROOT/resource.d/pacemaker/Dummy meta-data
----
[source,XML]
-------
<?xml version="1.0"?>
<!DOCTYPE resource-agent SYSTEM "ra-api-1.dtd">
<resource-agent name="Dummy" version="1.0">
<version>1.0</version>
<longdesc lang="en">
This is a Dummy Resource Agent. It does absolutely nothing except
keep track of whether its running or not.
Its purpose in life is for testing and to serve as a template for RA writers.
NB: Please pay attention to the timeouts specified in the actions
section below. They should be meaningful for the kind of resource
the agent manages. They should be the minimum advised timeouts,
but they shouldn't/cannot cover _all_ possible resource
instances. So, try to be neither overly generous nor too stingy,
but moderate. The minimum timeouts should never be below 10 seconds.
</longdesc>
<shortdesc lang="en">Example stateless resource agent</shortdesc>
<parameters>
<parameter name="state" unique="1">
<longdesc lang="en">
Location to store the resource state in.
</longdesc>
<shortdesc lang="en">State file</shortdesc>
<content type="string" default="/var/run/Dummy-default.state" />
</parameter>
<parameter name="fake" unique="0">
<longdesc lang="en">
Fake attribute that can be changed to cause a reload
</longdesc>
<shortdesc lang="en">Fake attribute that can be changed to cause a reload</shortdesc>
<content type="string" default="dummy" />
</parameter>
<parameter name="op_sleep" unique="1">
<longdesc lang="en">
Number of seconds to sleep during operations. This can be used to test how
the cluster reacts to operation timeouts.
</longdesc>
<shortdesc lang="en">Operation sleep duration in seconds.</shortdesc>
<content type="string" default="0" />
</parameter>
</parameters>
<actions>
<action name="start" timeout="20" />
<action name="stop" timeout="20" />
<action name="monitor" timeout="20" interval="10" depth="0"/>
<action name="reload" timeout="20" />
<action name="migrate_to" timeout="20" />
<action name="migrate_from" timeout="20" />
<action name="validate-all" timeout="20" />
<action name="meta-data" timeout="5" />
</actions>
</resource-agent>
-------
=====
-
- == Resource Operations ==
+
+
+.. _operation:
+
+Resource Operations
+###################
+
+
+.. Convert_to_RST_5:
indexterm:[Resource,Action]
'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).
.An OCF resource with a non-default start timeout
=====
[source,XML]
-------
<primitive id="Public-IP" class="ocf" type="IPaddr" provider="heartbeat">
<operations>
<op id="Public-IP-start" name="start" timeout="60s"/>
</operations>
<instance_attributes id="params-public-ip">
<nvpair id="public-ip-addr" name="ip" value="192.0.2.2"/>
</instance_attributes>
</primitive>
-------
=====
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
____________________
-.. Convert_to_RST_4:
+.. Convert_to_RST_6:
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.
.Properties of an Operation
[width="95%",cols="2m,3,<6",options="header",align="center"]
|=========================================================
|Field
|Default
|Description
|id
|
|A unique name for the operation.
indexterm:[id,Action Property]
indexterm:[Action,Property,id]
|name
|
|The action to perform. This can be any action supported by the agent; common
values include +monitor+, +start+, and +stop+.
indexterm:[name,Action Property]
indexterm:[Action,Property,name]
|interval
|0
|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 <<s-resource-monitoring,monitor>>.
indexterm:[interval,Action Property]
indexterm:[Action,Property,interval]
|timeout
|
|How long to wait before declaring the action has failed
indexterm:[timeout,Action Property]
indexterm:[Action,Property,timeout]
|on-fail
a|Varies by action:
* +stop+: +fence+ if +stonith-enabled+ is true or +block+ otherwise
* +demote+: +on-fail+ of the +monitor+ action with +role+ set to +Master+, if
present, enabled, and configured to a value other than +demote+, or +restart+
otherwise
* all other actions: +restart+
a|The action to take if this action ever fails. Allowed values:
* +ignore:+ Pretend the resource did not fail.
* +block:+ Don't perform any further operations on the resource.
* +stop:+ Stop the resource and do not start it elsewhere.
* +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 +Master+; for any other action, a configuration error will
be logged, and the default behavior will be used.
* +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.
indexterm:[on-fail,Action Property]
indexterm:[Action,Property,on-fail]
|enabled
|TRUE
|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 <<s-monitoring-unmanaged,not block any configured monitoring>>.
Disabling the operation does not suppress all actions of the given type.
Allowed values: +true+, +false+.
indexterm:[enabled,Action Property]
indexterm:[Action,Property,enabled]
|record-pending
|TRUE
|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 <<s-operation-defaults>>).
Allowed values: +true+, +false+.
indexterm:[enabled,Action Property]
indexterm:[Action,Property,enabled]
|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 <<s-resource-promotable,promotable clone resources>>, +Slave+ and +Master+.
indexterm:[role,Action Property]
indexterm:[Action,Property,role]
|=========================================================
[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 master scores have not
changed, it will be promoted again.
There is no direct equivalent of +migration-threshold+ for the master role, but
the same effect can be achieved with a location constraint using a
<<ch-rules,rule>> with a node attribute expression for the resource's fail
count.
For example, to immediately ban the master role from a node with any failed
promote or master monitor:
[source,XML]
----
<rsc_location id="loc1" rsc="my_primitive">
<rule id="rule1" score="-INFINITY" role="Master" boolean-op="or">
<expression id="expr1" attribute="fail-count-my_primitive#promote_0"
operation="gte" value="1"/>
<expression id="expr2" attribute="fail-count-my_primitive#monitor_10000"
operation="gte" value="1"/>
</rule>
</rsc_location>
----
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 master 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.
footnote:[Currently, anyway. Automatic monitoring operations may be
added in a future version of Pacemaker.]
You must configure +monitor+ operations explicitly to perform these checks.
.An OCF resource with a recurring health check
=====
[source,XML]
-------
<primitive id="Public-IP" class="ocf" type="IPaddr" provider="heartbeat">
<operations>
<op id="Public-IP-start" name="start" timeout="60s"/>
<op id="Public-IP-monitor" name="monitor" interval="60s"/>
</operations>
<instance_attributes id="params-public-ip">
<nvpair id="public-ip-addr" name="ip" value="192.0.2.2"/>
</instance_attributes>
</primitive>
-------
=====
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
<<s-resource-clone,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 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 the cluster is put into maintenance mode: All resources will be marked
as unmanaged. All monitor operations will be stopped, except those
specifying +role+ as +Stopped+ (which will be newly initiated if
appropriate). As with single unmanaged resources, starting
a resource on a node other than where the cluster expects it to be will
cause problems.
[[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,
----
# 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.
.An OCF resource with custom timeouts for its implicit actions
=====
[source,XML]
-------
<primitive id="Public-IP" class="ocf" type="IPaddr" provider="heartbeat">
<operations>
<op id="public-ip-startup" name="monitor" interval="0" timeout="90s"/>
<op id="public-ip-start" name="start" interval="0" timeout="180s"/>
<op id="public-ip-stop" name="stop" interval="0" timeout="15min"/>
</operations>
<instance_attributes id="params-public-ip">
<nvpair id="public-ip-addr" name="ip" value="192.0.2.2"/>
</instance_attributes>
</primitive>
-------
=====
=== 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.
.An OCF resource with two recurring health checks, performing different levels of checks specified via +OCF_CHECK_LEVEL+.
=====
[source,XML]
-------
<primitive id="Public-IP" class="ocf" type="IPaddr" provider="heartbeat">
<operations>
<op id="public-ip-health-60" name="monitor" interval="60">
<instance_attributes id="params-public-ip-depth-60">
<nvpair id="public-ip-depth-60" name="OCF_CHECK_LEVEL" value="10"/>
</instance_attributes>
</op>
<op id="public-ip-health-300" name="monitor" interval="300">
<instance_attributes id="params-public-ip-depth-300">
<nvpair id="public-ip-depth-300" name="OCF_CHECK_LEVEL" value="20"/>
</instance_attributes>
</op>
</operations>
<instance_attributes id="params-public-ip">
<nvpair id="public-ip-level" name="ip" value="192.0.2.2"/>
</instance_attributes>
</primitive>
-------
=====
=== 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.
.Example of an OCF resource with a disabled health check
=====
[source,XML]
-------
<primitive id="Public-IP" class="ocf" type="IPaddr" provider="heartbeat">
<operations>
<op id="public-ip-check" name="monitor" interval="60s" enabled="false"/>
</operations>
<instance_attributes id="params-public-ip">
<nvpair id="public-ip-addr" name="ip" value="192.0.2.2"/>
</instance_attributes>
</primitive>
-------
=====
This can be achieved from the command line by executing:
----
# cibadmin --modify --xml-text '<op id="public-ip-check" enabled="false"/>'
----
Once you've done whatever you needed to do, you can then re-enable it with
----
# cibadmin --modify --xml-text '<op id="public-ip-check" enabled="true"/>'
----
diff --git a/doc/sphinx/Pacemaker_Explained/utilization.rst b/doc/sphinx/Pacemaker_Explained/utilization.rst
index 4bcd777d62..3aa67adcac 100644
--- a/doc/sphinx/Pacemaker_Explained/utilization.rst
+++ b/doc/sphinx/Pacemaker_Explained/utilization.rst
@@ -1,232 +1,232 @@
+.. _utilization:
+
Utilization and Placement Strategy
----------------------------------
.. Convert_to_RST:
- [[s-utilization]]
-
Pacemaker decides where to place a resource according to the resource
allocation scores on every node. The resource will be allocated to the
node where the resource has the highest score.
If the resource allocation scores on all the nodes are equal, by the default
placement strategy, Pacemaker will choose a node with the least number of
allocated resources for balancing the load. If the number of resources on each
node is equal, the first eligible node listed in the CIB will be chosen to run
the resource.
Often, in real-world situations, different resources use significantly
different proportions of a node's capacities (memory, I/O, etc.).
We cannot balance the load ideally just according to the number of resources
allocated to a node. Besides, if resources are placed such that their combined
requirements exceed the provided capacity, they may fail to start completely or
run with degraded performance.
To take these factors into account, Pacemaker allows you to configure:
. The capacity a certain node provides.
. The capacity a certain resource requires.
. An overall strategy for placement of resources.
== Utilization attributes ==
To configure the capacity that a node provides or a resource requires,
you can use 'utilization attributes' in +node+ and +resource+ objects.
You can name utilization attributes according to your preferences and define as
many name/value pairs as your configuration needs. However, the attributes'
values must be integers.
.Specifying CPU and RAM capacities of two nodes
====
[source,XML]
----
<node id="node1" type="normal" uname="node1">
<utilization id="node1-utilization">
<nvpair id="node1-utilization-cpu" name="cpu" value="2"/>
<nvpair id="node1-utilization-memory" name="memory" value="2048"/>
</utilization>
</node>
<node id="node2" type="normal" uname="node2">
<utilization id="node2-utilization">
<nvpair id="node2-utilization-cpu" name="cpu" value="4"/>
<nvpair id="node2-utilization-memory" name="memory" value="4096"/>
</utilization>
</node>
----
====
.Specifying CPU and RAM consumed by several resources
====
[source,XML]
----
<primitive id="rsc-small" class="ocf" provider="pacemaker" type="Dummy">
<utilization id="rsc-small-utilization">
<nvpair id="rsc-small-utilization-cpu" name="cpu" value="1"/>
<nvpair id="rsc-small-utilization-memory" name="memory" value="1024"/>
</utilization>
</primitive>
<primitive id="rsc-medium" class="ocf" provider="pacemaker" type="Dummy">
<utilization id="rsc-medium-utilization">
<nvpair id="rsc-medium-utilization-cpu" name="cpu" value="2"/>
<nvpair id="rsc-medium-utilization-memory" name="memory" value="2048"/>
</utilization>
</primitive>
<primitive id="rsc-large" class="ocf" provider="pacemaker" type="Dummy">
<utilization id="rsc-large-utilization">
<nvpair id="rsc-large-utilization-cpu" name="cpu" value="3"/>
<nvpair id="rsc-large-utilization-memory" name="memory" value="3072"/>
</utilization>
</primitive>
----
====
A node is considered eligible for a resource if it has sufficient free
capacity to satisfy the resource's requirements. The nature of the required
or provided capacities is completely irrelevant to Pacemaker -- it just makes
sure that all capacity requirements of a resource are satisfied before placing
a resource to a node.
== Placement Strategy ==
After you have configured the capacities your nodes provide and the
capacities your resources require, you need to set the +placement-strategy+
in the global cluster options, otherwise the capacity configurations have
'no effect'.
Four values are available for the +placement-strategy+:
+default+::
Utilization values are not taken into account at all.
Resources are allocated according to allocation scores. If scores are equal,
resources are evenly distributed across nodes.
+utilization+::
Utilization values are taken into account 'only' when deciding whether a node
is considered eligible (i.e. whether it has sufficient free capacity to satisfy
the resource's requirements). Load-balancing is still done based on the
number of resources allocated to a node.
+balanced+::
Utilization values are taken into account when deciding whether a node
is eligible to serve a resource 'and' when load-balancing, so an attempt is
made to spread the resources in a way that optimizes resource performance.
+minimal+::
Utilization values are taken into account 'only' when deciding whether a node
is eligible to serve a resource. For load-balancing, an attempt is made to
concentrate the resources on as few nodes as possible, thereby enabling
possible power savings on the remaining nodes.
Set +placement-strategy+ with `crm_attribute`:
----
# crm_attribute --name placement-strategy --update balanced
----
Now Pacemaker will ensure the load from your resources will be distributed
evenly throughout the cluster, without the need for convoluted sets of
colocation constraints.
== Allocation Details ==
=== Which node is preferred to get consumed first when allocating resources? ===
- The node with the highest node weight gets consumed first. Node weight
is a score maintained by the cluster to represent node health.
- If multiple nodes have the same node weight:
* If +placement-strategy+ is +default+ or +utilization+,
the node that has the least number of allocated resources gets consumed first.
** If their numbers of allocated resources are equal,
the first eligible node listed in the CIB gets consumed first.
* If +placement-strategy+ is +balanced+,
the node that has the most free capacity gets consumed first.
** If the free capacities of the nodes are equal,
the node that has the least number of allocated resources gets consumed first.
*** If their numbers of allocated resources are equal,
the first eligible node listed in the CIB gets consumed first.
* If +placement-strategy+ is +minimal+,
the first eligible node listed in the CIB gets consumed first.
=== Which node has more free capacity? ===
If only one type of utilization attribute has been defined, free capacity
is a simple numeric comparison.
If multiple types of utilization attributes have been defined, then
the node that is numerically highest in the the most attribute types
has the most free capacity. For example:
- If +nodeA+ has more free +cpus+, and +nodeB+ has more free +memory+,
then their free capacities are equal.
- If +nodeA+ has more free +cpus+, while +nodeB+ has more free +memory+ and +storage+,
then +nodeB+ has more free capacity.
=== Which resource is preferred to be assigned first? ===
- The resource that has the highest +priority+ (see <<s-resource-options>>) gets allocated first.
- If their priorities are equal, check whether they are already running. The
resource that has the highest score on the node where it's running gets allocated
first, to prevent resource shuffling.
- If the scores above are equal or the resources are not running, the resource has
the highest score on the preferred node gets allocated first.
- If the scores above are equal, the first runnable resource listed in the CIB
gets allocated first.
== Limitations and Workarounds ==
The type of problem Pacemaker is dealing with here is known as the
http://en.wikipedia.org/wiki/Knapsack_problem[knapsack problem] and falls into
the http://en.wikipedia.org/wiki/NP-complete[NP-complete] category of computer
science problems -- a fancy way of saying "it takes a really long time
to solve".
Clearly in a HA cluster, it's not acceptable to spend minutes, let alone hours
or days, finding an optimal solution while services remain unavailable.
So instead of trying to solve the problem completely, Pacemaker uses a
'best effort' algorithm for determining which node should host a particular
service. This means it arrives at a solution much faster than traditional
linear programming algorithms, but by doing so at the price of leaving some
services stopped.
In the contrived example at the start of this chapter:
- +rsc-small+ would be allocated to +node1+
- +rsc-medium+ would be allocated to +node2+
- +rsc-large+ would remain inactive
Which is not ideal.
There are various approaches to dealing with the limitations of
pacemaker's placement strategy:
Ensure you have sufficient physical capacity.::
It might sound obvious, but if the physical capacity of your nodes is (close to)
maxed out by the cluster under normal conditions, then failover isn't going to
go well. Even without the utilization feature, you'll start hitting timeouts and
getting secondary failures.
Build some buffer into the capabilities advertised by the nodes.::
Advertise slightly more resources than we physically have, on the (usually valid)
assumption that a resource will not use 100% of the configured amount of
CPU, memory and so forth 'all' the time. This practice is sometimes called 'overcommit'.
Specify resource priorities.::
If the cluster is going to sacrifice services, it should be the ones you care
about (comparatively) the least. Ensure that resource priorities are properly set
so that your most important resources are scheduled first.

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