VERITAS Volume Manager 3.1 Administrator's Guide

Recovery
Miscellaneous RAID-5 Operations
Chapter 8 377
marked as STALE and then recovered using VOL_R5_RECOVER
operations. Recovery is done either by the vxsd utility or (if the volume is
not active) when the volume is started. This means that the RAID-5
volume is degraded for the duration of the operation .
Another failure in the stripes involved in the move makes the volume
unusable. The RAID-5 volume can also become invalid if the parity of the
volume becomes stale.
To avoid these situations, the vxsd utility does not allow a subdisk move
if:
• a stale subdisk occupies any of the same stripes as the subdisk being
moved
• the RAID-5 volume is stopped but was not shut down cleanly (parity
is considered stale)
• the RAID-5 volume is active and has no valid log areas
Only the third case can be overridden by using the -o force option.
Subdisks of RAID-5 volumes can also be split and joined by using the
vxsd split command and the vxsd join command. These operations
work the same way as those for mirrored volumes.
NOTE RAID-5 subdisk moves are performed the same as other subdisk moves
without the penalty of degraded redundancy.
Starting RAID-5 Volumes
When a RAID-5 volume is started, it can be in one of many states. After a
normal system shutdown, the volume should be clean and require no
recovery. However, if the volume was not closed, or was not unmounted
before a crash, it can require recovery when it is started, before it can be
made available. This section describes actions that can be taken under
certain conditions.
Under normal conditions, volumes are started automatically after a
reboot and any recovery takes place automatically or is done through the
vxrecover command.