Quorum and Connectivity Needed for Quorum
Applies To: Windows Server 2008 R2
A failover cluster can run only when a majority of cluster elements (a quorum) are running and in communication. These elements usually include the nodes and, with some quorum configurations, a witness disk (which contains a copy of the cluster configuration) or witness file share. When enough of these elements are running and in communication, the cluster has achieved quorum and can run.
|The Cluster service is shutting down because quorum was lost. This could be due to the loss of network connectivity between some or all nodes in the cluster, or a failover of the witness disk.
Run the Validate a Configuration wizard to check your network configuration. If the condition persists, check for hardware or software errors related to the network adapter. Also check for failures in any other network components to which the node is connected such as hubs, switches, or bridges.