Veritas Volume Manager 5.0 Troubleshooting Guide, HP-UX 11i v3, First Edition, May 2008

18 Recovery from hardware failure
Failures on RAID-5 volumes
2 Any existing log plexes are zeroed and enabled. If all logs fail during this
process, the start process is aborted.
3 If no stale subdisks exist or those that exist are recoverable, the volume is
put in the ENABLED volume kernel state and the volume state is set to
ACTIVE. The volume is now started.
Recovering a RAID-5 volume
The types of recovery that may typically be required for RAID-5 volumes are the
following:
■ Parity resynchronization
■ Log plex recovery
■ Stale subdisk recovery
Parity resynchronization and stale subdisk recovery are typically performed
when the RAID-5 volume is started, or shortly after the system boots. They can
also be performed by running the vxrecover command.
For more information on starting RAID-5 volumes, see “Starting RAID-5
volumes” on page 21.
If hot-relocation is enabled at the time of a disk failure, system administrator
intervention is not required unless no suitable disk space is available for
relocation. Hot-relocation is triggered by the failure and the system
administrator is notified of the failure by electronic mail.
Hot relocation automatically attempts to relocate the subdisks of a failing RAID-
5 plex. After any relocation takes place, the hot-relocation daemon (vxrelocd)
also initiates a parity resynchronization.
In the case of a failing RAID-5 log plex, relocation occurs only if the log plex is
mirrored; the vxrelocd daemon then initiates a mirror resynchronization to
recreate the RAID-5 log plex. If hot-relocation is disabled at the time of a failure,
the system administrator may need to initiate a resynchronization or recovery.
Note: Following severe hardware failure of several disks or other related
subsystems underlying a RAID-5 plex, it may be impossible to recover the
volume using the methods described in this chapter. In this case, remove the
volume, recreate it on hardware that is functioning correctly, and restore the
contents of the volume from a backup.