Configuring the quorum device for high availability

Either a single basic disk used as a physical disk resource or a volume located on a three-disk SFW cluster disk group can serve as the Microsoft clustering quorum device.

In general, a disk group containing a dedicated, three-way mirrored volume makes an ideal quorum device. In Microsoft clustering environments, the proper configuration of a quorum device is critical to providing the highest availability with SFW storage.

Using a single disk as the quorum device introduces a nonredundant component into an otherwise highly available system. A failure-tolerant volume used as a quorum device provides a level of availability that is consistent with that of the rest of the cluster.

An SFW cluster disk group containing a volume used as a quorum device should contain that volume only. Any other volumes in that disk group fail over whenever the quorum device changes ownership.

A disk group containing only a three-way mirrored volume makes an ideal quorum device. Such a device tolerates both disk failures, because it is mirrored, and server and interconnect failures, because SFW can import it when the disks and at least one server are running.

For a server to take ownership of a disk group containing the cluster quorum device, SFW must successfully import the disk group, and obtain SCSI reservations on more than half of its disks. Disk groups containing odd numbers of disks are best for use as quorum devices because of this behavior.