Make sure that the I/O fencing coordinator disks meet the following requirements:

• For disk-based I/O fencing, you must have three coordinator disks.

• The coordinator disks can be raw devices, DMP devices, or iSCSI devices.

• Each of the coordinator disks must use a physically separate disk or LUN.

  Symantec recommends using the smallest possible LUNs for coordinator disks.

• Each of the coordinator disks should exist on a different disk array, if possible.

• The coordinator disks must support SCSI-3 persistent reservations.

• Symantec recommends using hardware-based mirroring for coordinator disks.

• Coordinator disks must not be used to store data or must not be included in disk groups that store user data.

• Coordinator disks cannot be the special devices that array vendors use. For example, you cannot use EMC gatekeeper devices as coordinator disks.