Veritas Storage Foundation Intelligent Storage Provisioning 5.0.1 Administrators Guide, HP-UX 11i v3, First Edition, November 2009

Use the following command to add a version 20 DCO and DCO volume to an existing
volume:
# vxassist [-g diskgroup] [-P storage_pool] addlog volume \
[nlog=number] logtype=dco [regionsize=size] \
[drl=yes|no|sequential]
The nlog attribute specifies the number of DCO plexes that are created in the DCO
volume. It is recommended that you configure as many DCO plexes as there are
data plexes in the volume. For example, specify nlog=3 for a volume with 3 data
plexes.
The value of the regionsize attribute specifies the size of the tracked regions in
the volume. A write to a region is tracked by setting a bit in the change map. The
default value is 64k (64KB). A smaller value requires more disk space for the change
maps, but the finer granularity provides faster resynchronization.
To enable DRL logging on the volume, specify drl=yes. If sequential DRL is
required, specify drl=sequential.
You can also specify vxassist-style storage attributes to define the disks that
can and/or cannot be used for the plexes of the DCO volume.
Removing support for DRL and snapshots from a volume
To remove support for DCO-based DRL and instant snapshots from a volume, use
the following command to remove the DCO and DCO volume that are associated
with the volume:
# vxassist [-g diskgroup] [-P storage_pool] removeall log \
volume logtype=dco
This command fails if the volume is part of a snapshot hierarchy.
Evacuating a volume
If you need to remove or disable a disk, you must first move any data off the disk
by evacuating it. Similarly, if the whole or parts of a volume are configured on
disks that are needed for other purposes, or which are not optimal or appropriate
for use by the volume, you can evacuate these.
To evacuate certain disks on which a volume is configured, use either of the
following commands to specify the disks to evacuate:
# vxassist [-g diskgroup] [-b] evacuate disk volume \
!dmname ... [use_storage=rule[,...]] [attributes...]
83Administering application volumes
Evacuating a volume