Quorum in a two-node cluster

You learned about quorum in Chapter 2, Meet the Cluster Stack on CentOS. Quorum is the minimum number of cluster member votes required to perform a cluster operation. Without quorum, the cluster cannot operate. Quorum is achieved when the majority of cluster members vote to execute a specific cluster operation. If the majority of the cluster members do not vote, the cluster operation will not be performed.

You've probably understood where this is going. In a two-node cluster configuration, the maximum number of expected votes is two—each cluster node has one vote. In a cluster node failure scenario, only one cluster node is active and it has only one vote. In such a configuration, quorum cannot be reached, since a majority of the votes cannot be delivered. The single cluster node is stuck at 50 percent and will never get past it. Therefore, the cluster will never operate normally this way. Luckily, there are solutions to work around this problem...