Veritas Volume Manager 5.1 SP1 Administrator"s Guide (5900-1506, April 2011)

the move. You can use the vxprint command on a volume to examine the
configuration of its associated DCO volume.
If you use the vxassist command to create both a volume and its DCO, or the
vxsnap prepare command to add a DCO to a volume, the DCO plexes are
automatically placed on different disks from the data plexes of the parent volume.
In previous releases, version 0 DCO plexes were placed on the same disks as the
data plexes for convenience when performing disk group split and move operations.
As version 20 DCOs support dirty region logging (DRL) in addition to Persistent
FastResync, it is preferable for the DCO plexes to be separated from the data
plexes. This improves the performance of I/O from/to the volume, and provides
resilience for the DRL logs.
Figure 6-7 shows some instances in which it is not be possible to split a disk group
because of the location of the DCO plexes on the disks of the disk group.
For more information about snapshots and DCO volumes, see the Veritas Storage
Foundation Advanced Features Administrator's Guide.
See “Specifying storage for version 20 DCO plexes” on page 360.
See “FastResync” on page 63.
See “Volume snapshots” on page 60.
Creating and administering disk groups
Reorganizing the contents of disk groups
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