An operation that was attempted as part of a backup or restore did not succeed. Check for the following preconditions to make sure they have been met, and then retry the backup or restore operation:
The cluster must achieve quorum. In other words, enough nodes must be running and communicating (perhaps with a witness disk or witness file share, depending on the quorum configuration) that the cluster has achieved a majority, that is, quorum. For more information about quorum, with the Failover Cluster Management snap-in open, click Help, click Help Topics, click the Search tab, and search for quorum. Open the topic called Understanding Quorum Configurations in a Failover Cluster.
The account used by the person performing the backup must be in the local Administrators group on each clustered server, and must be a domain account, or must have been delegated the equivalent authority.