In a cluster environment with 2 or more instances where a quorum loss situation has occurred, it may not be enough to restart the affected appliance(s) to get the cluster back to normal. It is possible that such reboot results in the following message being displayed
"Warning: PAM-CS-0010: The following primary site cluster members are no longer participating in database replication: <IP_MEMBER>: MISSING".
CA PAM 3.3.X
There is special logic in place when rebooting instances in a cluster where the nodes try to find each other in the first 5 minutes afterwards. Rebooting a single node may result in this behaviour do to ambiguities in the mechanism. Rebooting both nodes, with no confusion added may help to resolve the quorum loss and may allow cluster to start normally in sync.