CMAN & Two-Nodes cluster: prevent rgmanager “Quorum Dissolved”.

Ordinarily, the loss of quorum after one out of two nodes fails will prevent the remaining node from continuing (if both nodes have one vote.)

Special configuration options can be set to allow the one remaining node to continue operating if the other fails.

To do this only two nodes, each with one vote, can be defined in cluster.conf.
The two_node and expected_votes values must then be set to 1 in the cman section as follows:

<cman two_node="1" expected_votes="1"></cman>

This setup can be useful in Proxmox VE 2 nodes HA Environment, to prevent unwanted VM Shutdown/Start sequence on alive node.
In fact, if this configuration is not applied and a node change its state, unwanted reboots of HA VMs will occur, since the rgmanager Quorum is considered not satisfied (Dissolved).

Note: Proper fence actions need to be set and tested to set a reliable HA Cluster.


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