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

21Recovery from hardware failure
Failures on RAID-5 volumes
Any failure in the stripes involved in the move makes the volume unusable. The
RAID-5 volume can also become invalid if its parity becomes stale. To avoid this
occurring,
vxsd does not allow a subdisk move in the following situations:
■ 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; that is, the
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 in the same way as subdisk moves
for other volume types, but 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.
Unstartable RAID-5 volumes
A RAID-5 volume is unusable if some part of the RAID-5 plex does not map the
volume length:
■ the RAID-5 plex cannot be sparse in relation to the RAID-5 volume length
■ the RAID-5 plex does not map a region where two subdisks have failed
within a stripe, either because they are stale or because they are built on a
failed disk
When this occurs, the
vxvol start command returns the following error
message:
VxVM vxvol ERROR V-5-1-1236 Volume r5vol is not startable; RAID-
5 plex does not map entire volume length.
At this point, the contents of the RAID-5 volume are unusable.