VERITAS Volume Manager 3.5 Administrator's Guide (September 2004)

Conﬁguring Off-Host Processing

Implementing Off-Host Processing Solutions

Chapter 11380

Implementing Decision Support

This section describes a procedure for implementing off-host decision

support for a volume in a private disk group. The intention is to present

an outline of how to set up a replica database by combining the

Persistent FastResync and disk group split and join features of VxVM. It

is beyond the scope of this guide to describe how to conﬁgure a database

to use this procedure.

To set up a replica database using the table ﬁles that are conﬁgured

within a volume in a private disk group, use the following procedure.

Step 1. Use the following command on the primary host to see if the volume is

associated with a data change object (DCO) and DCO volume that allow

Persistent FastResync to be used with the volume:

# vxprint -g volumedg -F%hasdcolog volume

This command returns on if there is a DCO and DCO volume; otherwise,

it returns off.

If the volume is not associated with a DCO object and DCO volume,

follow the procedure described in “Adding a DCO and DCO Volume” on

page 263.

Step 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 Persistent FastResync is disabled, enable it using the following

command on the master host:

# vxvol -g volumedg set fastresync=on volume

Step 3. If the volume does not already contain a snapshot plex, create one using

the following command on the primary host:

# vxassist -g volumedg [-b] snapstart [nmirror=N] volume

The vxassist snapstart task creates a write-only mirror, which is

attached to and synchronized from the volume to be backed up.