witness file share (n)~ For a failover cluster a file share in the cluster storage that is designated to hold information about the cluster configuration database. A failover cluster has a witness file share only if this is specified as part of the quorum configuration. witness server (n)~ In database mirroring the server instance that monitors the status of the principal and mirror servers and that by default can initiate automatic failover if the principal server fails. A database mirroring session can have only one witness server (or witness’)