Filter
Top Products
276 Administering volumes
Preparing a volume for DRL and instant snapshots
Note: The vxsnap prepare command automatically enables Persistent
FastResync on the volume. Persistent FastResync is also set automatically on
any snapshots that are generated from a volume on which this feature is
enabled.
If the volume is a RAID-5 volume, it is converted to a layered volume that can be
used with instant snapshots and Persistent FastResync. See “Using a DCO and
DCO volume with a RAID-5 volume” on page 277 for details.
By default, a version 20 DCO volume contains 32 per-volume maps. If you
require more maps than this, you can use the
vxsnap addmap command to add
more maps. See the vxsnap(1M) manual page for details of this command.
Specifying storage for version 20 DCO plexes
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 mirrored DCO volume with plexes on disk05
and disk06 to the volume, myvol, use the following command:
# vxsnap -g mydg prepare myvol ndcomirs=2 alloc=disk05,disk06
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 vol1 (the TUTIL0 and PUTIL0 columns are
omitted for clarity):
TY NAME ASSOC KSTATE LENGTH PLOFFS STATE ...
v vol1 fsgen ENABLED 1024 - ACTIVE
pl vol1-01 vol1 ENABLED 1024 - ACTIVE
sd disk01-01 vol1-01 ENABLED 1024 0 -
pl foo-02 vol1 ENABLED 1024 - ACTIVE
sd disk02-01 vol1-02 ENABLED 1024 0 -
dc vol1_dco vol1 - - - -
v vol1_dcl gen ENABLED 132 - ACTIVE
pl vol1_dcl-01 vol1_dcl ENABLED 132 - ACTIVE
sd disk03-01 vol1_dcl-01ENABLED 132 0 -
pl vol1_dcl-02 vol1_dcl ENABLED 132 - ACTIVE
sd disk04-01 vol1_dcl-02ENABLED 132 0 -
In this output, the DCO object is shown as vol1_dco, and the DCO volume as
vol1_dcl with 2 plexes, vol1_dcl-01 and vol1_dcl-02.