VERITAS Volume Manager 3.1 Administrator's Guide

Recovery
Miscellaneous RAID-5 Operations
Chapter 8378
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: 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. This situation is shown in Figure 8-1,
Invalid RAID-5 Volume, which shows a RAID-5 volume that has become
invalid due to stale parity and a failed subdisk.