Veritas Volume Manager 5.0.1 Administrator's Guide, HP-UX 11i v3, First Edition, November 2009

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.

Note: The ! character is a special character in some shells. The following

example shows how to escape it in a bash shell.

# vxprint [-g diskgroup] -F "%name" \

-e "v_fastresync=on && \!v_hasdcolog"

Use the following command to add a DCO and DCO volume to the existing

volume (which may already have dirty region logging (DRL) enabled):

# vxassist [-g diskgroup] addlog volume logtype=dco \

[ndcomirror=number] [dcolen=size] [storage_attributes]

For non-layered volumes, the default number of plexes in the mirrored DCO

volume is equal to the lesser of the number of plexes in the data volume or

2. For layered volumes, the default number of DCO plexes is always 2. If

required, use the ndcomirror attribute to specify a different number. It is

recommended that you configure as many DCO plexes as there are existing

data and snapshot plexes in the volume. For example, specify ndcomirror=3

when adding a DCO to a 3-way mirrored volume.

The default size of each plex is 132 blocks. You can use the dcolen attribute

to specify a different size. If specified, the size of the plex must be an integer

multiple of 33 blocks from 33 up to a maximum of 2112 blocks.

You can specify vxassist-style storage attributes to define the disks that can

and/or cannot be used for the plexes of the DCO volume.

See “Specifying storage for version 0 DCO plexes” on page 407.

Specifying storage for version 0 DCO plexes

If the disks that contain volumes and their snapshots are to be moved or split into

different disk groups, the disks that contain their respective DCO plexes must be

able to accompany them. By default, VxVM attempts to place version 0 DCO plexes

on the same disks as the data plexes of the parent volume. However, this may be

impossible if there is insufficient space available on those disks. In this case, VxVM

uses any available space on other disks in the disk group. If the DCO plexes are

407Administering volume snapshots

Adding a version 0 DCO and DCO volume