Veritas Volume Manager 4.1 Troubleshooting Guide (HP-UX 11i v3, February 2007)

Failures on RAID-5 Volumes
12 VERITAS Volume Manager Troubleshooting Guide
The volume is not made available while the parity is resynchronized because any
subdisk failures during this period makes the volume unusable. This can be
overridden by using the -o unsafe start option with the vxvol command. If any
stale subdisks exist, the RAID-5 volume is unusable.
Caution The -o unsafe start option is considered dangerous, as it can make the
contents of the volume unusable. Using it is not recommended.
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 15.
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.