Persistent Reserve errors

You can use Persistent Reserve (PR) to provide faster failover times between disks that support this feature. PR allows the stripe group manager to "fence" disks during node failover by removing the reservation keys for that node. In contrast, non-PR disk failovers cause the system to wait until the disk lease expires.

GPFS allows file systems to have a mix of PR and non-PR disks. In this configuration, GPFS will fence PR disks for node failures and recovery and non-PR disk will use disk leasing. If all of the disks are PR disks, disk leasing is not used, so recovery times improve.

GPFS uses the mmchconfig command to enable PR. Issuing this command with the appropriate usePersistentReserve option configures disks automatically. If this command fails, the most likely cause is either a hardware or device driver problem. Other PR-related errors will probably be seen as file system unmounts that are related to disk reservation problems. This type of problem should be debugged with existing trace tools.