VERITAS Volume Manager 3.5 Administrator's Guide (September 2002)

Chapter 8, Administering Volumes
Adding a DCO and DCO Volume
195
To view the details of the DCO objectand DCOvolume thatare associated witha volume,
use the vxprint command. The following is example vxprint output for the volume
named zoo (the TUTIL0 and PUTIL0 columns are omitted for clarity):
TY NAME ASSOC KSTATE LENGTH PLOFFS STATE ...
v zoo fsgen ENABLED 1024 - ACTIVE
pl zoo-01 zoo ENABLED 1024 - ACTIVE
sd c1t66d0-02 zoo-01 ENABLED 1024 0 -
pl foo-02 zoo ENABLED 1024 - ACTIVE
sd c1t67d0-02 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 c1t66d0-01 zoo_dcl-01 ENABLED 132 0 -
pl zoo_dcl-02 zoo_dcl ENABLED 132 - ACTIVE
sd c1t67d0-01 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.
For more information, see the vxassist(1M) manual page.
Attaching a DCO and DCO volume to a RAID-5 Volume
The procedure in the previous section can be used to add a DCO and DCO volume to a
RAID-5 volume. This allows you to enable Persistent FastResync on the volume for fast
resynchronization of snapshots on snapback (see “Enabling FastResync on a Volume” on
page 207). However, the procedure has the side effect of converting the RAID-5 volume
into a special type of layered volume. You cannot relayout or resize such a volume unless
you convert it back to a pure RAID-5 volume. To do this, remove any snapshot plexes
from the volume, and dissociate the DCO and DCO volume from the layered volume
using the procedure described in “Removing a DCO and DCO Volume” on page 196. You
can then perform relayout and resize operations on the resulting non-layered RAID-5
volume.
To allow Persistent FastResync to be used with the RAID-5 volume again, re-associate the
DCO and DCO volume as described in “Reattaching a DCO and DCO Volume” on
page 197.
Note Dissociating a DCO and DCO volume disables Persistent FastResync on the
volume. A fullresynchronizationof any remainingsnapshots is requiredwhen they
are snapped back.