Chapter 3. The pcs command-line interface

You use the -h option of pcs to display the parameters of a pcs command and a description of those parameters.

The following command displays the parameters of the pcs resource command.

# pcs resource -h

Although you should not edit the cluster configuration file directly, you can view the raw cluster configuration with the pcs cluster cib command.

You can save the raw cluster configuration to a specified file with the pcs cluster cib filename command. If you have previously configured a cluster and there is already an active CIB, you use the following command to save the raw xml file.

pcs cluster cib filename

For example, the following command saves the raw xml from the CIB into a file named testfile.

# pcs cluster cib testfile

When configuring a cluster, you can save configuration changes to a specified file without affecting the active CIB. This allows you to specify configuration updates without immediately updating the currently running cluster configuration with each individual update.

For information about saving the CIB to a file, see Viewing the raw cluster configuration. Once you have created that file, you can save configuration changes to that file rather than to the active CIB by using the -f option of the pcs command. When you have completed the changes and are ready to update the active CIB file, you can push those file updates with the pcs cluster cib-push command.

Alternately, you can push the entire current content of a CIB file with the following command.

pcs cluster cib-push filename

When pushing the entire CIB file, Pacemaker checks the version and does not allow you to push a CIB file which is older than the one already in a cluster. If you need to update the entire CIB file with a version that is older than the one currently in the cluster, you can use the --config option of the pcs cluster cib-push command.

pcs cluster cib-push --config filename

There are a variety of commands you can use to display the status of a cluster and its components.

You can display the status of the cluster and the cluster resources with the following command.

# pcs status

You can display the status of a particular cluster component with the commands parameter of the pcs status command, specifying resources, cluster, nodes, or pcsd.

pcs status commands

For example, the following command displays the status of the cluster resources.

# pcs status resources

The following command displays the status of the cluster, but not the cluster resources.

# pcs cluster status

If you run the pcs status command before Pacemaker has completed any actions required by changes to the CIB, the cluster state at that time might not match the desired status. In RHEL Hat Enterprixe Linux 9.5 and later, you can ensure that Pacemaker does not need to take any further actions by running the pcs status wait command.

The pcs status wait command waits until the cluster has completed all current actions before returning a value. If any actions unrelated to your recent changes are in progress, the command waits until those are completed. The pcs status wait command returns a value of 0 as soon as Pacemaker completes pending actions.

You can specify a period of time to wait. If the current actions have not completed after that time period, the command prints an error and returns a value of 1.

The following command waits until Pacemaker has applied configuration changes.

# pcs status wait
Waiting for the cluster to apply configuration changes...

The following command waits up to one minute until Pacemaker has applied configuration changes.

# pcs status wait 1min
Waiting for the cluster to apply configuration changes (timeout: 60 seconds)...

Use the following command to display the full current cluster configuration.

# pcs config

In a complex cluster setup, you might need to determine the status of an individual resource in a cluster before performing a cluster or resource action. In Red Hat Enterprise Linux 9.5 and later, you can query various attributes of a single resource in a cluster with the pcs status query resource commands. You can use these commands for pcs-based scripting because there is no need to parse plain text outputs.

The pcs status query resource commands query the following attributes:

The following command queries whether a resource has started.

# pcs status query resource RESOURCE_ID is-state started

For example, the following command queries whether the resource resource1 has started.

# pcs status query resource resource1 is-state started
True

For a full list of the pcs status query resource commands, see the pcs(8) man page on your system.

You can use the pcs command to modify the parameters in the corosync.conf file.

The following command modifies the parameters in the corosync.conf file.

pcs cluster config update [transport pass:quotes[transport options]] [compression pass:quotes[compression options]] [crypto pass:quotes[crypto options]] [totem pass:quotes[totem options]] [--corosync_conf pass:quotes[path]]

The following example command udates the knet_pmtud_interval transport value and the token and join totem values.

# pcs cluster config update transport knet_pmtud_interval=35 totem token=10000 join=100

The following command displays the contents of the corosync.conf cluster configuration file.

# pcs cluster corosync

You can print the contents of the corosync.conf file in a human-readable format with the pcs cluster config command, as in the following example.

The output for this command includes the UUID for the cluster if the cluster was created in RHEL 9.1 or later, or if the UUID was added manually as described in Identifying clusters by UUID.

[root@r8-node-01 ~]# pcs cluster config
Cluster Name: HACluster
Cluster UUID: ad4ae07dcafe4066b01f1cc9391f54f5
Transport: knet
Nodes:
  r8-node-01:
    Link 0 address: r8-node-01
    Link 1 address: 192.168.122.121
    nodeid: 1
  r8-node-02:
    Link 0 address: r8-node-02
    Link 1 address: 192.168.122.122
    nodeid: 2
Links:
  Link 1:
    linknumber: 1
    ping_interval: 1000
    ping_timeout: 2000
    pong_count: 5
Compression Options:
  level: 9
  model: zlib
  threshold: 150
Crypto Options:
  cipher: aes256
  hash: sha256
Totem Options:
  downcheck: 2000
  join: 50
  token: 10000
Quorum Device: net
  Options:
    sync_timeout: 2000
    timeout: 3000
  Model Options:
    algorithm: lms
    host: r8-node-03
  Heuristics:
    exec_ping: ping -c 1 127.0.0.1

You can run the pcs cluster config show command with the --output-format=cmd option to display the pcs configuration commands that can be used to recreate the existing corosync.conf file, as in the following example.

[root@r8-node-01 ~]# pcs cluster config show --output-format=cmd
pcs cluster setup HACluster \
  r8-node-01 addr=r8-node-01 addr=192.168.122.121 \
  r8-node-02 addr=r8-node-02 addr=192.168.122.122 \
  transport \
  knet \
    link \
      linknumber=1 \
      ping_interval=1000 \
      ping_timeout=2000 \
      pong_count=5 \
    compression \
      level=9 \
      model=zlib \
      threshold=150 \
    crypto \
      cipher=aes256 \
      hash=sha256 \
  totem \
    downcheck=2000 \
    join=50 \
    token=10000