Veritas Storage Foundation 5.1 SP1 Advanced Features Administrator"s Guide (5900-1503, April 2011)

To view the details of the DCO object and DCO volume that are associated with a
volume, use the vxprint command. The following is example vxprint -vh output
for the volume named zoo (the TUTIL0 and PUTIL0 columns are omitted for
clarity):
TTY NAME ASSOC KSTATE LENGTH PLOFFS STATE
...
v zoo fsgen ENABLED 1024 - ACTIVE
pl zoo-01 zoo ENABLED 1024 - ACTIVE
sd disk01-01 zoo-01 ENABLED 1024 0 -
pl zoo-02 zoo ENABLED 1024 - ACTIVE
sd disk02-01 zoo-02 ENABLED 1024 0 -
dc zoo_dco zoo - - - -
v zoo_dcl gen ENABLED 132 - ACTIVE
pl zoo_dcl-01 zoo_dcl ENABLED 132 - ACTIVE
sd disk03-01 zoo_dcl-01 ENABLED 132 0 -
pl zoo_dcl-02 zoo_dcl ENABLED 132 - ACTIVE
sd disk04-01 zoo_dcl-02 ENABLED 132 0 -
In this output, the DCO object is shown as zoo_dco, and the DCO volume as zoo_dcl
with 2 plexes, zoo_dcl-01 and zoo_dcl-02.
See “Considerations for placing DCO plexes” on page 147.
For more information on DCO objects, see the vxassist(1M) and vxsnap(1M)
manual pages.
Considerations for placing DCO plexes
If you use the vxassist command or the Veritas Operations Manager VOM) to
create both a volume and its DCO, or the vxsnap prepare command to add a DCO
to a volume, the DCO plexes are automatically placed on different disks from the
data plexes of the parent volume. In previous releases, version 0 DCO plexes were
placed on the same disks as the data plexes for convenience when performing
disk group split and move operations. As the version 20 DCOs in VxVM 4.0 and
later releases support dirty region logging (DRL) in addition to persistent
FastResync, it is preferable for the DCO plexes to be separated from the data
plexes. This improves the I/O performance of the volume, and provides resilience
for the DRL logs.
If you use the vxsnap prepare command to set up a DCO, you must ensure that
the disks that contain the plexes of the DCO volume accompany their parent
volume during the move. Use the vxprint command on a volume to examine the
configuration of its associated DCO volume.
147Setting up volumes for instant snapshots
Preparing a volume for instant snapshot operations