Chapter 3. The pcs command-line interface The pcs command-line interface controls and configures cluster services such as corosync , pacemaker , booth , and sbd by providing an easier interface to their configuration files. Note that you should not edit the cib.xml configuration file directly. In most cases, Pacemaker will reject a directly modified cib.xml file. 3.1. pcs help display 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. 3.2. Viewing the raw cluster configuration 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. For example, the following command saves the raw xml from the CIB into a file named testfile . 3.3. Saving a configuration change to a working file 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. Procedure The following is the recommended procedure for pushing changes to the CIB file. This procedure creates a copy of the original saved CIB file and makes changes to that copy. When pushing those changes to the active CIB, this procedure specifies the diff-against option of the pcs cluster cib-push command so that only the changes between the original file and the updated file are pushed to the CIB. This allows users to make changes in parallel that do not overwrite each other, and it reduces the load on Pacemaker which does not need to parse the entire configuration file. Save the active CIB to a file. This example saves the CIB to a file named original.xml . Copy the saved file to the working file you will be using for the configuration updates. Update your configuration as needed. The following command creates a resource in the file updated.xml but does not add that resource to the currently running cluster configuration. Push the updated file to the active CIB, specifying that you are pushing only the changes you have made to the original file. Alternately, you can push the entire current content of a CIB file with the following command. 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. 3.4. Displaying cluster status 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. 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 . For example, the following command displays the status of the cluster resources. The following command displays the status of the cluster, but not the cluster resources. 3.5. Displaying the full cluster configuration Use the following command to display the full current cluster configuration. 3.6. Modifying the corosync.conf file with the pcs command As of Red Hat Enterprise Linux 8.4, 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. The following example command udates the knet_pmtud_interval transport value and the token and join totem values. Additional resources For information about adding and removing nodes from an existing cluster, see Managing cluster nodes . For information about adding and modifying links in an existing cluster, see Adding and modifying links in an existing cluster . For information about modifyng quorum options and managing the quorum device settings in a cluster, see Configuring cluster quorum and Configuring quorum devices . 3.7. Displaying the corosync.conf file with the pcs command The following command displays the contents of the corosync.conf cluster configuration file. As of Red Hat Enterprise Linux 8.4, 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 8.7 or later or if the UUID was added manually as described in Identifying clusters by UUID . As of RHEL 8.4, 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.

Commands:
pcs resource -h
pcs cluster cib filename
pcs cluster cib testfile
pcs cluster cib original.xml
cp original.xml updated.xml
pcs -f updated.xml resource create VirtualIP ocf:heartbeat:IPaddr2 ip=192.168.0.120 op monitor interval=30s
pcs cluster cib-push updated.xml diff-against=original.xml
pcs cluster cib-push filename
pcs cluster cib-push --config filename
pcs status
pcs status commands
pcs status resources
pcs cluster status
pcs config
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 ]]
pcs cluster config update transport knet_pmtud_interval=35 totem token=10000 join=100
pcs cluster corosync
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
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