What is a “Persistent Reservation” (PR)?
A PR is a SCSI command, which clustering uses to protect LUN’s. When a LUN is reserved, no other computers on the SAN can access the disk, except the ones cluster controls. This is important to protect other machines from accessing the disk and corrupting the data on the disk.
Validate a Cluster Configuration is a functional test tool that verifies that your storage supports all the necessary SCSI commands that clustering requires. It is critical that Validate tests pass, for your cluster to work correctly. The Storage tests are by far the most important, they should not be dismissed!
This test validates that the cluster storage uses the more recent (SCSI-3 standard) Persistent Reserve commands (which are different from the older SCSI-2 standard reserve/release commands). The Persistent Reserve commands avoid SCSI bus resets, which means they are much less disruptive than the older reserve/release commands. Therefore, a failover cluster can be more responsive in a variety of situations, as compared to a cluster running an earlier version of the operating system. In addition, disks are never left in an unprotected state, which lowers the risk of volume corruption
