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356 Administering volume snapshots
Adding a version 0 DCO and DCO volume
Adding a version 0 DCO and DCO volume
Note: The procedure described in this section adds a DCO log volume that has a
version 0 layout as introduced in VxVM 3.2. The version 0 layout supports
traditional (third-mirror break-off) snapshots, but not full-sized or space-
optimized instant snapshots. See “Version 0 DCO volume layout” on page 69 and
“Version 20 DCO volume layout” on page 69 for a description of the differences
between the old and new DCO volume layouts.
See “Determining the DCO version number” on page 277 for details of how to
determine the version number of a volume’s DCO.
To put Persistent FastResync into effect for a volume, a Data Change Object
(DCO) and DCO volume must first be associated with that volume. When you
have added a DCO object and DCO volume to a volume, you can then enable
Persistent FastResync on the volume as described in “Enabling FastResync on a
volume” on page 292.
Note: You need a Veritas FlashSnap
TM
or FastResync license to use the
FastResync feature. Even if you do not have a license, you can configure a DCO
object and DCO volume so that snap objects are associated with the original and
snapshot volumes. For more information about snap objects, see “How
persistent FastResync works with snapshots” on page 70.
To add a DCO object and DCO volume to an existing volume (which may already
have dirty region logging (DRL) enabled), use the following procedure:
1 Ensure that the disk group containing the existing volume has been
upgraded to at least version 90. Use the following command to check the
version of a disk group:
# vxdg list diskgroup
To upgrade a disk group to the latest version, use the following command:
# vxdg upgrade diskgroup
For more information, see “Upgrading a disk group” on page 208.
2 Use the following command to turn off Non-Persistent FastResync on the
original volume if it is currently enabled:
# vxvol [-g diskgroup] set fastresync=off volume
If you are uncertain about which volumes have Non-Persistent FastResync
enabled, use the following command to obtain a listing of such volumes:
# vxprint [-g diskgroup] -F “%name” \
-e “v_fastresync=on && !v_hasdcolog”