"Ring ID" from "pcs quorum status"

[Emanuel_Haine]

Hi everyone!

I have a question and I hope you can help me with that.

When I run "pcs quorum status" there is a field called "Ring ID". I noticed the value is the same for all nodes in the cluster and it changes when a cluster is rebooted/fenced and when it rejoins in the cluster.

I tried to find some documentation regarding this specific field but I didn't find anything that could explain it. Do the "Ring ID" values mean something? I am wondering if it can be helpful in a troubleshooting scenario.

[Wasim_Raja · Accepted solution]

The “Ring ID” field in the output of the pcs quorum status command refers to the unique identifier of the corosync ring. The corosync ring is a communication channel used by the nodes in the cluster to exchange messages and maintain quorum.

The ring ID is the same for all nodes in the cluster because they are all part of the same ring. When the cluster is rebooted/fenced and rejoins, the ring ID changes because the ring is recreated.

The ring ID is not used for troubleshooting purposes, but it can be helpful in understanding the communication between the nodes in the cluster.

Regards,

Wasim

[Chetan_Tiwary_]

Yes @Emanuel_Haine it might be helpful in troubleshooting scenarios. 

Incompatibility between corosync versions leads to cluster dysfunction. Nodes running different versions cannot form a viable cluster. Worse, if such a node departs, the remaining nodes inherit a gargantuan and unpredictable ring ID, jeopardizing cluster stability and quorum calculations. In that case you will need to remove the unoredictable ring ID from the /var/lib/corosync directory and pacemaker and dlm needs to be updated. 

There may be other scenarios as well.