Veritas Volume Manager 4.1 Administrator's Guide (HP-UX 11i v3, February 2007)

Chapter 9, Administering Volume Snapshots

Adding a Version 0 DCO and DCO Volume

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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 “Versi on 0 DCO Volume La you t ” on page 51 and “Version 20 DCO

Volume Layout” on page 51 for a description of the differences between the old and

new DCO volume layouts.

See “Determining the DCO Version Number” on page 238 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 252.

Note You need a VERITAS FlashSnap

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 53.

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 169.

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”