VERITAS FlashSnap Point-In-Time-Copy Solutions Administrator's Guide

Preparing a Volume for Instant Snapshot Operations
20 VERITAS FlashSnap Point-In-Time Copy Solutions Administrator’s Guide
# vxsnap -g mydg addmir vol1 nmirror=2 alloc=mydg10,mydg11
Note Do not perform this step if you create a full-sized snapshot volume using a suitably
prepared empty volume (see “Creating a Volume for Use as a Full-Sized Instant
Snapshot” on page 23), or if you create space-optimized snapshots that use a cache (see
“Creating a Shared Cache Object” on page 24).
If the disks that contain volumes and their snapshots are to be moved into different disk groups, you
must ensure that the disks that contain their DCO plexes can accompany them. You can use storage
attributes to specify which disks to use for the DCO plexes. (If you do not want to use dirty region
logging (DRL) with a volume, you can specify the same disks as those on which the volume is
configured, assuming that space is available on the disks). For example, to add a DCO object and
DCO volume with plexes on disk05 and disk06, and a region size of 32KB, to the volume,
myvol, use the following command:
# vxsnap -g mydg prepare myvol ndcomirs=2 regionsize=32k \
alloc=disk05,disk06
If required, you can use the vxassist move command to relocate DCO plexes to different disks.
For example, the following command moves the plexes of the DCO volume for volume vol1 from
disk03 and disk04 to disk07 and disk08:
# vxassist -g mydg move vol1_dcl !disk03 !disk04 disk07 disk08
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):
TY 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 foo-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 disk 04-01 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 “Considerations for Placing DCO Plexes” on page 21, and the
vxassist(1M) and vxsnap(1M) manual pages.