VERITAS Volume Manager 4.1 Administrator's Guide

Administering Volumes
Adding DRL Logging to a Mirrored Volume
Chapter 8 283
Adding DRL Logging to a Mirrored Volume
To put dirty region logging (DRL) into effect for a mirrored volume, a log
subdisk must be added to that volume. Only one log subdisk can exist per
plex.
To add DRL logs to an existing volume, use the following command:
# vxassist [-b] addlog volume logtype=drl [nlog=n]
NOTE If specified, the -b option makes adding the new logs a background task.
The nlog attribute can be used to specify the number of log plexes to add.
By default, one log plex is added. For example, to add a single log plex for
the volume vol03, use the following command:
# vxassist addlog vol03 logtype=drl
When the vxassist command is used to add a log subdisk to a volume, by
default a log plex is also created to contain the log subdisk unless you
include the keyword nolog in the layout specification.
For a volume that will be written to sequentially, such as a database log
volume, include the logtype=drlseq attribute to specify that sequential
DRL is to be used:
# vxassist addlog volume logtype=drlseq [nlog=n]
Once created, the plex containing a log subdisk can be treated as a
regular plex. Data subdisks can be added to the log plex. The log plex
and log subdisk can be removed using the same procedures as are used to
remove ordinary plexes and subdisks.