Veritas Volume Manager 5.0.1 Troubleshooting Guide, HP-UX 11i v3, First Edition, November 2009

■ 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.
RAID-5 subdisk moves are performed in the same way as subdisk moves for other
volume types, but without the penalty of degraded redundancy.
Unstartable 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.
Under normal conditions, volumes are started automatically after a reboot and
any recovery takes place automatically or is done through the vxrecover command.
A RAID-5 volume is unusable if some part of the RAID-5 plex does not map the
volume length in the following circumstances:
■ The RAID-5 plex is 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.
Another possible way that a RAID-5 volume can become unstartable is if the parity
is stale and a subdisk becomes detached or stale. This occurs because within the
stripes that contain the failed subdisk, the parity stripe unit is invalid (because
the parity is stale) and the stripe unit on the bad subdisk is also invalid.
Figure 1-3 illustrates a RAID-5 volume that has become invalid due to stale parity
and a failed subdisk.
25Recovering from hardware failure
Failures on RAID-5 volumes