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

sd disk02-01 r5vol-01 disk02 0 102400 1/0 c2t10d0 dS
sd disk03-01 r5vol-01 disk03 0 102400 2/0 c2t11d0 ENA
...
This output lists the volume state as NEEDSYNC, indicating that the parity needs
to be resynchronized. The state could also have been SYNC, indicating that a
synchronization was attempted at start time and that a synchronization process
should be doing the synchronization. If no such process exists or if the volume is
in the NEEDSYNC state, a synchronization can be manually started by using the
resync keyword for the vxvol command.
Parity is regenerated by issuing VOL_R5_RESYNC ioctls to the RAID-5 volume.
The resynchronization process starts at the beginning of the RAID-5 volume and
resynchronizes a region equal to the number of sectors specified by the -o iosize
option. If the -o iosize option is not specified, the default maximum I/O size is
used. The resync operation then moves onto the next region until the entire length
of the RAID-5 volume has been resynchronized.
For larger volumes, parity regeneration can take a long time. It is possible that
the system could be shut down or crash before the operation is completed. In case
of a system shutdown, the progress of parity regeneration must be kept across
reboots. Otherwise, the process has to start all over again.
To avoid the restart process, parity regeneration is checkpointed. This means that
the offset up to which the parity has been regenerated is saved in the configuration
database. The -o checkpt=size option controls how often the checkpoint is saved.
If the option is not specified, the default checkpoint size is used.
Because saving the checkpoint offset requires a transaction, making the checkpoint
size too small can extend the time required to regenerate parity. After a system
reboot, a RAID-5 volume that has a checkpoint offset smaller than the volume
length starts a parity resynchronization at the checkpoint offset.
To resynchronize parity on a RAID-5 volume
◆
Type the following command:
# vxvol -g diskgroup resync r5vol
Reattaching a failed RAID-5 log plex
RAID-5 log plexes can become detached due to disk failures. These RAID-5 logs
can be reattached by using the att keyword for the vxplex command.
23Recovering from hardware failure
Failures on RAID-5 volumes