Use the following guidelines when setting up quorum devices:
Establish a quorum device between all nodes that are attached to the same shared disk storage enclosure. Add one disk within the shared enclosure as a quorum device to ensure that if any node fails, the other nodes can maintain quorum and master the disk device groups on the shared enclosure.
You must connect the quorum device to at least two nodes.
A quorum device can be any SCSI-2 or SCSI-3 disk used as a dual-ported quorum device. Disks connected to more than two nodes must support SCSI-3 Persistent Group Reservation (PGR) regardless of whether the disk is used as a quorum device. See the chapter on planning in the Sun Cluster 3.1 Software Installation Guide for more information.
You can use a disk that contains user data as a quorum device.