Symantec Veritas Cluster Server One, Installation Manual

Page: 105 / 210

105 Adding shared storage and testing disks for SCSI-3 compliance
About VCS One client I/O fencing
About VCS One client I/O fencing
If a system in the VCS One cluster loses connectivity with Policy Master cluster,
I/O fencing prevents shared storage from being corrupted. The I/O fencing
mechanism for client systems is based on SCSI-3 persistent reservations.
Consider the following scenario. Multiple systems in the VCS One cluster use a
common shared storage. Due to a network fault, one of these systems loses its
connectivity with the Policy Master cluster.
In the meantime, the Policy Master does not receive heartbeat signals from the
disconnected system and instructs another system on the service group’s
SystemList to force import the shared disk group. The other SystemList system
invalidates the disconnected system’s registration keys on the shared storage
and replaces them with its own. The service group that includes the storage
resource then fails over to the other system.