VERITAS Volume Manager 3.1 Administrator's Guide

Recovery
Miscellaneous RAID-5 Operations
Chapter 8 375
Miscellaneous RAID-5 Operations
NOTE You may need an additional license to use this feature.
Many operations exist for manipulating RAID-5 volumes and associated
objects. These operations are usually performed by other commands,
such as the vxassist command and the vxrecover command, as part of
larger operations, such as evacuating disks. These command line
operations are not necessary for light usage of the Volume Manager.
Manipulating RAID-5 Logs
RAID-5 logs are represented as plexes of RAID-5 volumes and are
manipulated using the vxplex command. To a RAID-5 log can be added,
use the following command:
# vxplex att r5vol r5log
The attach (att) operation can only proceed if the size of the new log is
large enough to hold all of the data on the stripe. If the RAID-5 volume
already contains logs, the new log length is the minimum of each
individual log length. This is because the new log is a mirror of the old
logs.
If the RAID-5 volume is not enabled, the new log is marked as BADLOG
and is enabled when the volume is started. However, the contents of the
log are ignored.
If the RAID-5 volume is enabled and has other enabled RAID-5 logs, the
new log has its contents synchronized with the other logs through
ATOMIC_COPY ioctls.
If the RAID-5 volume currently hasno enabledlogs, thenew logis zeroed
before it is enabled.
Log plexes can be removed from a volume using the following command:
# vxplex dis r5log3
When removing the log leaves the volume with less than two valid logs, a
warning is printed and the operation is not allowed to continue. The
operation must be forced by using the -o force option.