Quorum

The quorum resource maintains the cluster database, as well as critical recovery information, in a recovery log. The quorum resource has to be available to all nodes through a SCSI or Fibre Channel bus. With Microsoft clustering alone, the quorum disk must be located on a single physical disk. However, with SFW, the quorum disk can be a mirrored volume that spans multiple disks and cluster nodes.

The quorum resource also determines ownership of the cluster. When a node that is controlling the cluster goes offline, other nodes use a challenge/defense protocol to determine which node can have control of the quorum resource and the cluster.