Chapter 16. Managing cluster resources

To display a list of all configured resources, use the following command.

pcs resource status

For example, if your system is configured with a resource named VirtualIP and a resource named WebSite, the pcs resource status command yields the following output.

# pcs resource status
 VirtualIP	(ocf::heartbeat:IPaddr2):	Started
 WebSite	(ocf::heartbeat:apache):	Started

To display the configured parameters for a resource, use the following command.

pcs resource config resource_id

For example, the following command displays the currently configured parameters for resource VirtualIP.

# pcs resource config VirtualIP
 Resource: VirtualIP (type=IPaddr2 class=ocf provider=heartbeat)
  Attributes: ip=192.168.0.120 cidr_netmask=24
  Operations: monitor interval=30s

As of RHEL 8.5, to display the status of an individual resource, use the following command.

pcs resource status resource_id

For example, if your system is configured with a resource named VirtualIP the pcs resource status VirtualIP command yields the following output.

# pcs resource status VirtualIP
 VirtualIP      (ocf::heartbeat:IPaddr2):       Started

As of RHEL 8.5, to display the status of the resources running on a specific node, use the following command. You can use this command to display the status of resources on both cluster and remote nodes.

pcs resource status node=node_id

For example, if node-01 is running resources named VirtualIP and WebSite the pcs resource status node=node-01 command might yield the following output.

# pcs resource status node=node-01
 VirtualIP      (ocf::heartbeat:IPaddr2):       Started
 WebSite        (ocf::heartbeat:apache):        Started

To modify the parameters of a configured resource, use the following command.

pcs resource update resource_id [resource_options]

The following sequence of commands show the initial values of the configured parameters for resource VirtualIP, the command to change the value of the ip parameter, and the values following the update command.

# pcs resource config VirtualIP
 Resource: VirtualIP (type=IPaddr2 class=ocf provider=heartbeat)
  Attributes: ip=192.168.0.120 cidr_netmask=24
  Operations: monitor interval=30s
# pcs resource update VirtualIP ip=192.169.0.120
# pcs resource config VirtualIP
 Resource: VirtualIP (type=IPaddr2 class=ocf provider=heartbeat)
  Attributes: ip=192.169.0.120 cidr_netmask=24
  Operations: monitor interval=30s

If a resource has failed, a failure message appears when you display the cluster status. If you resolve that resource, you can clear that failure status with the pcs resource cleanup command. This command resets the resource status and failcount, telling the cluster to forget the operation history of a resource and re-detect its current state.

The following command cleans up the resource specified by resource_id.

pcs resource cleanup resource_id

If you do not specify a resource_id, this command resets the resource status and failcountfor all resources.

The pcs resource cleanup command probes only the resources that display as a failed action. To probe all resources on all nodes you can enter the following command:

pcs resource refresh

By default, the pcs resource refresh command probes only the nodes where a resource’s state is known. To probe all resources even if the state is not known, enter the following command:

pcs resource refresh --full

Pacemaker provides a variety of mechanisms for configuring a resource to move from one node to another and to manually move a resource when needed.

You can manually move resources in a cluster with the pcs resource move and pcs resource relocate commands, as described in Manually moving cluster resources. In addition to these commands, you can also control the behavior of cluster resources by enabling, disabling, and banning resources, as described in Disabling, enabling, and banning cluster resources.

You can configure a resource so that it will move to a new node after a defined number of failures, and you can configure a cluster to move resources when external connectivity is lost.

# pcs resource meta dummy_resource migration-threshold=10

# pcs resource defaults update migration-threshold=10

# pcs resource create ping ocf:pacemaker:ping dampen=5s multiplier=1000 host_list=gateway.example.com clone

# pcs constraint location Webserver rule score=-INFINITY pingd lt 1 or not_defined pingd

The easiest way to stop a recurring monitor is to delete it. However, there can be times when you only want to disable it temporarily. In such cases, add enabled="false" to the operation’s definition. When you want to reinstate the monitoring operation, set enabled="true" to the operation’s definition.

When you update a resource’s operation with the pcs resource update command, any options you do not specifically call out are reset to their default values. For example, if you have configured a monitoring operation with a custom timeout value of 600, running the following commands will reset the timeout value to the default value of 20 (or whatever you have set the default value to with the pcs resource op defaults command).

# pcs resource update resourceXZY op monitor enabled=false
# pcs resource update resourceXZY op monitor enabled=true

In order to maintain the original value of 600 for this option, when you reinstate the monitoring operation you must specify that value, as in the following example.

# pcs resource update resourceXZY op monitor timeout=600 enabled=true

As of Red Hat Enterprise Linux 8.3, you can use the pcs command to tag cluster resources. This allows you to enable, disable, manage, or unmanage a specified set of resources with a single command.