VERITAS Volume Manager 4.1 Administrator's Guide

Administering Volumes
Enabling Persistent FastResync on Existing Volumes with Associated Snapshots
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use the disk group move feature to bring in spare disks from a different
disk group. For more information, see “Reorganizing the Contents of
Disk Groups” on page 172.
Perform the following steps to enable Persistent FastResync on an
existing volume that has attached snapshot plexes or associated
snapshot volumes:
Step 1. Upgrade the disk group containing the existing volume to at least
version 90 before performing the remainder of the procedure described in
this section. 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 190.
Step 2. For a volume that has one or more associated snapshot volumes, it is
recommended that you use following command to reattach and
resynchronize each snapshot:
# vxassist [-g diskgroup] snapback snapvol
If Non-Persistent FastResync was enabled on the volume before the
snapshot was taken, the data in the snapshot plexes is quickly
resynchronized from the original volume. If Non-Persistent FastResync
was not enabled, a full resynchronization is performed.
If you choose to reattach all the snapshots, you need only add a DCO and
DCO volume to the original volume.
If you choose not to snapback the snapshot volumes, you must add a
DCO and DCO volume to the original volume, and separately to each of
its snapshot volumes. This approach requires a full resynchronization on
the first subsequent snapback of each snapshot volume after you have
enabled Persistent FastResync.
Step 3. Use the following command to turn off Non-Persistent FastResync on the
original volume if it is currently enabled: