VERITAS Volume Manager 4.1 Administrator's Guide

Administering Volumes
Adding a DCO and DCO Volume
Chapter 8278
Step 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”
Step 3. Use the following command to add a DCO and DCO volume to the
existing volume:
# 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 a integer multiple of 33 blocks from 33 up to a maximum of 2112
blocks.
To view the details of the DCO object and DCO volume that are
associated with a volume, use the vxprint command. The following is
example vxprint output for the volume named zoo (the TUTIL0 and
PUTIL0 columns are omitted for clarity):
TY NAME ASSOC KSTATE LENGTH PLOFFS STATE ...
v zoo fsgen ENABLED 1024 - ACTIVE
pl zoo-01 zoo ENABLED 1024 - ACTIVE
sd c1t66d0-02 zoo-01 ENABLED 1024 0 -
pl foo-02 zoo ENABLED 1024 - ACTIVE
sd c1t67d0-02 zoo-02 ENABLED 1024 0 -
dc zoo_dco zoo - - - -
v zoo_dcl gen ENABLED 132 - ACTIVE
pl zoo_dcl-01 zoo_dcl ENABLED 132 - ACTIVE
sd c1t66d0-01 zoo_dcl-01 ENABLED 132 0 -