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

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 4-7 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.
See “Specifying storage for version 0 DCO plexes” on page 407.
See “Specifying storage for version 20 DCO plexes” on page 319.
See “FastResync” on page 65.
See “Volume snapshots” on page 63.
233Creating and administering disk groups
Reorganizing the contents of disk groups