VERITAS Volume Manager 3.5 Administrator's Guide (September 2002)

Creating a Mirrored Volume

172 VERITAS Volume Manager Administrator’s Guide

To create a volume with an attached DCO object and DCO volume, use the following

procedure:

1. Ensurethat the disk grouphas been upgradedto atleast version 90. Usethe 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 133.

2. Use the following command to createthe volume(you mayneed tospecify additional

attributes to create a volume with the desired characteristics):

# vxassist [-g diskgroup] make volume length layout=layout \

logtype=dco [ndcomirror=number] [dcolen=size] [fastresync=on]

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 data plexes in the volume. For example,

specify ndcomirror=3 when creating a 3-way mirrored volume.

The default size of each plex is 132 blocks unless you use the dcolen attribute to

specify adifferent size. If speciﬁed, the size of theplex mustbe amultiple of 33 blocks

from 33 up to a maximum of 2112 blocks.

By default, FastResync is not enabled on newly created volumes. Specify the

fastresync=on attribute if you want to also enable FastResync on the volume. If a

DCO object and DCO volume are associated with the volume, Persistent FastResync

is enabled; otherwise, Non-Persistent FastResync is enabled.

For more information about conﬁguring DCO, see the vxassist(1M) manual page.

Creating a Mirrored Volume with DRL Logging Enabled

To create a mirrored volume with dirty region logging (DRL) enabled, use this command:

# vxassist [-g diskgroup] make volume length layout=mirror \

logtype=drl

Note By default, the vxassist command creates one log plex for a mirrored volume.