10.8. Each Node in a Two-Node Cluster Reports Second Node Down

If your cluster is a two-node cluster and each node reports that it is up but that the other node is down, this indicates that your cluster nodes are unable to communicate with each other by means of multicast over the cluster heartbeat network. This is known as "split brain" or a "network partition." To address this, check the conditions outlined in Section 10.2, “Cluster Does Not Form”.