How do i add or remove support for RRP on a existing pacemaker cluster?

Environment

• Red Hat Enterprise Linux Server 6 and 7 (with the High Availability Add On)
• pacemaker

Issue

• How do i remove RRP from my pacemaker cluster?
• How do i add or remove support for RRP on a existing pacemaker cluster?

Resolution

The only way to add or remove rings for RRP (when there is multiple rings) to an existing pacemaker cluster is to modify the file /etc/corosync/corosync.conf manual.

• Stop the pacemaker and corosyncservices on all cluster nodes:

  # pcs cluster stop --all

• Edit the file /etc/corosync/corosync.conf and save the file. In the configuration file you either add a new ring or you will remove an existing ring. For example to remove one of the rings from all the cluster nodes then you would run the command:

  # sed -i.bak '/ring1_addr/d' /etc/corosync/corosync.conf

  If rings are going to be added so that cluster is using RRP then review an example configuration file shown in the following article: How can I configure a redundant heartbeat network for a RHEL 6 or 7 High Availability cluster?

• Then scp the saved file /etc/corosync/corosync.conf to all the nodes in the cluster.

• Start the pacemaker and corosync services on all cluster nodes:

  # pcs cluster start --all

To verify if one or more rings are being then they can run the following command (corosync-cfgtool -s) to check each cluster node as long as they can ssh into the cluster node and it is a current member of the cluster:

# for h in $(grep ring0_addr /etc/corosync/corosync.conf | cut -d ":" -f 2); do echo $h; ssh $h "corosync-cfgtool -s"; done

Root Cause

There is currently no way to modify an existing cluster to add or remove rings in pacemaker cluster with pcs command.

Additional Information:

Redundant Ring Protocol ( RRP ) Is not supported in RHEL 8+. Due to this, this solution is only applicable for RHEL 6 and 7:

• Support Policies for RHEL High Availability Clusters - Cluster Interconnect Network Interfaces

This solution is part of Red Hat’s fast-track publication program, providing a huge library of solutions that Red Hat engineers have created while supporting our customers. To give you the knowledge you need the instant it becomes available, these articles may be presented in a raw and unedited form.