Veritas Volume Manager 5.0 Administrator's Guide (September 2006)

366 Configuring off-host processing
Implementing off-host processing solutions
To set up a replica database using the table files that are configured within a volume
in a private disk group
1 Use the following command on the primary host to see if the volume is associated
with a version 20 data change object (DCO) and DCO volume that allow instant
snapshots and Persistent FastResync to be used with the volume:
# vxprint -g volumedg -F%instant volume
This command returns on if the volume can be used for instant snapshot operations;
otherwise, it returns off.
Note: If the volume was created under VxVM 4.0 or a later release, and it is not
associated with a new-style DCO object and DCO volume, follow the procedure
described in “Preparing a volume for DRL and instant snapshots” on page 267.
If the volume was created before release 4.0 of VxVM, and has any attached snapshot
plexes, or is associated with any snapshot volumes, follow the procedure given in
“Upgrading existing volumes to use version 20 DCOs” on page 271.
2 Use the following command on the primary host to check whether FastResync is
enabled on a volume:
# vxprint -g volumedg -F%fastresync volume
This command returns on if FastResync is enabled; otherwise, it returns off.
If FastResync is disabled, enable it using the following command on the primary
host:
# vxvol -g volumedg set fastresync=on volume
3 Prepare the OHP host to receive the snapshot volume that contains the copy of the
database tables. This may involve setting up private volumes to contain any redo
logs, and configuring any files that are used to initialize the database.
4 On the primary host, create a new volume in a separate disk group for use as the
snapshot volume as described in “Creating a volume for use as a full-sized instant or
linked break-off snapshot” on page 315. It is recommended that a snapshot disk
group is dedicated to maintaining only those disks that are used for off-host
processing.
5 On the primary host, link the snapshot volume in the snapshot disk group to the data
volume:
# vxsnap -g volumedg -b addmir volume mirvol=snapvol \
mirdg=snapvoldg
You can use the vxsnap snapwait command to wait for synchronization of the
linked snapshot volume to complete:
# vxsnap -g volumedg snapwait volume mirvol=snapvol \
mirdg=snapvoldg