What is a Cluster Resource

What is a Cluster Resource - The role of a resource agent is to abstract the service it provides and present a consistent view to the cluster, which allows the cluster to be agnostic about the resources it manages. + The role of a resource agent is to abstract 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. @@ -172,9 +172,9 @@ What state should the cluster attempt to keep this resource in? Allowed values: - Stopped - Force the resource to - Started - Allow the resource to be started (In the case of multi-state resources, they will not promoted to master) - Master - Allow the resource to be started and, if appropriate, promoted + Stopped - Force the resource to be stopped. + Started - Allow the resource to be started. In the case of multi-state resources, they will not be promoted to master. + Master - Allow the resource to be started and if appropriate be promoted @@ -183,7 +183,7 @@ TRUE Is the cluster allowed to start and stop the resource? - Allowed values: true, false + Allowed values: true, false. @@ -191,7 +191,7 @@ Inherited How much does the resource prefer to stay where it is? - Defaults to the value of resource-stickiness in the rsc_defaults section + Defaults to the value of resource-stickiness in the rsc_defaults section. @@ -202,7 +202,7 @@ failure-timeout 0 (disabled) - 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. + 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. multiple-active @@ -210,9 +210,9 @@ 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 + 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. @@ -323,7 +323,7 @@

Monitoring Resources for Failure - By default, the cluster will not ensure your resources are still healthy. + By default, the cluster will not ensure your resources stay healthy. To instruct the cluster to do this, you need to add a monitor operation to the resource's definition. @@ -355,7 +355,7 @@ name - The action to perform. Common values: monitor, start, stop + The action to perform. Common values: monitor, start, stop. interval @@ -403,11 +403,11 @@

Setting Global Defaults for Operations - To set a default value for a operation option, simply add it to the op_defaults section with crm_attribute. Thus, + To set a default value for an operation option simply add it to the op_defaults section with crm_attribute. Thus, crm_attribute --type op_defaults --attr-name timeout --attr-value 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 instead (for that operation only). + would default every operation's timeout to 20 seconds. + If an operation's definition also includes a value for timeout, then that value takes precedence.

When Resources Take a Long Time to Start/Stop @@ -436,7 +436,7 @@

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. + 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. @@ -477,7 +477,7 @@ 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 disabled="true" to the operation's definition. + In such cases, simply add enabled="false" to the operation's definition. Example of an OCF resource with a disabled health check @@ -485,7 +485,7 @@ - + @@ -495,9 +495,9 @@ This can be achieved from the command-line by executing - cibadmin -M -X ‘<op id="public-ip-check" disabled="true"/>' + cibadmin -M -X ‘<op id="public-ip-check" abled="false"/>' Once you've done whatever you needed to do, you can then re-enable it with - cibadmin -M -X ‘<op id="public-ip-check" disabled="false"/>' + cibadmin -M -X ‘<op id="public-ip-check" enabled="true"/>'