VERITAS FlashSnap Point-In-Time-Copy Solutions Administrator's Guide

Additional Preparation Activities
18 VERITAS FlashSnap Point-In-Time Copy Solutions Administrator’s Guide
Additional Preparation Activities
Depending on the type of snapshots that you want to create, you may need to perform additional
preparatory tasks.
When creating a full-sized instant snapshot, you can use one of the following two methods:
◆ Break off one or more spare plexes from the original volume to form a snapshot volume with
the required redundancy. These plexes must be in the SNAPDONE state. (You can also break off
named plexes of a volume that are in the ACTIVE state, but that method is not described here.
For more information, see the “Administering Volume Snapshots” chapter in the VERITAS
Volume Manager Administrator’s Guide.)
◆ Use a separate empty volume that you have prepared in advance as described in “Creating a
Volume for Use as a Full-Sized Instant Snapshot” on page 23.
When creating space-optimized instant snapshots that share a cache, you must set up the cache
before creating the snapshots. See “Creating a Shared Cache Object” on page 24 for details.
If a space-optimized instant snapshot uses a dedicate cache, this can also be set up when the
snapshot is created. No additional preparation is required in this case.
Note The off-host processing solutions in this book require full-sized snapshots.
Preparing a Volume for Instant Snapshot Operations
To prepare a volume for instant snapshot operations, a version 20 Data Change Object (DCO) and
DCO volume must first be associated with that volume.
To add a version 20 DCO object and DCO volume to an existing volume, use the following
procedure:
1. Ensure that the disk group containing the existing volume has been upgraded to at least version
110. Use the following command to check the version of a disk group:
# vxprint -l diskgroup | egrep ’version:’