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

Removing a DCO and DCO Volume
196 VERITAS Volume Manager Administrator’s Guide
Specifying Storage for 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 the 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 placed on disks which are used to
hold the plexes of other volumes, this may cause problems when you subsequently
attempt to move volumes into other disk groups.
You can use storage attributes to specify explicitly which disks to use for the DCO plexes.
If possible, specify the same disks as those on which the volume is configured. For
example, to add a DCO object and DCO volume with plexes on disk5 and disk6, and a
plex size of 264 blocks to the volume, myvol, use the following command:
# vxassist -g mydg addlog myvol logtype=dco dcolen=264 \
disk5 disk6
If required, you can use the vxassist move command to relocate DCO plexes to
different disks. For example, the following command moves the plexes of the DCO
volume for volume vol1 from disk3 and disk4 to disk7 and disk8:
# vxassist -g mydg move vol1_dcl !disk3 !disk4 disk7 disk8
For more information, see “Considerations for Placing DCO Plexes” on page 126.
Removing a DCO and DCO Volume
To dissociate a DCO object, DCO volume and any snap objects from a volume, use the
following command:
# vxassist [-g diskgroup] remove log volume logtype=dco
This completely removes the DCO object, DCO volume and any snap objects. It also has
the effect of disabling FastResync for the volume.
Alternatively, you can use the vxdco command to the same effect:
# vxdco [-g diskgroup] [-o rm] dis dco_obj
The default name of the DCO object, dco_obj, for a volume is usually formed by
appending the string _dco to the name of the parent volume. To find out the name of the
associated DCO object, use the vxprint command on the volume.
To dissociate, but not remove, the DCO object, DCO volume and any snap objects from
the volume, myvol, in the disk group, mydg, use the following command:
# vxdco -g mydg dis myvol_dco