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

For example, the following command would add the subdisk, mydg11-01, to the
end of column 1 of the plex, vol02-01:
# vxsd -g mydg -l 1 assoc vol02-01 mydg11-01
Alternatively, to add M subdisks at the end of each of the N columns in a striped
or RAID-5 volume, you can use the following form of the vxsd command:
# vxsd [-g diskgroup] assoc plex subdisk1:0 ... subdiskM:N-1
The following example shows how to append three subdisk to the ends of the three
columns in a striped plex, vol-01, in the disk group, mydg:
# vxsd -g mydg assoc vol01-01 mydg10-01:0 mydg11-01:1 mydg12-01:2
If a subdisk is filling a “hole” in the plex (that is, some portion of the volume logical
address space is mapped by the subdisk), the subdisk is considered stale. If the
volume is enabled, the association operation regenerates data that belongs on the
subdisk. Otherwise, it is marked as stale and is recovered when the volume is
started.
Associating log subdisks
Log subdisks are defined and added to a plex that is to become part of a volume
on which dirty region logging (DRL) is enabled. DRL is enabled for a volume when
the volume is mirrored and has at least one log subdisk.
Warning: Only one log subdisk can be associated with a plex. Because this log
subdisk is frequently written, care should be taken to position it on a disk that is
not heavily used. Placing a log subdisk on a heavily-used disk can degrade system
performance.
See “Dirty region logging” on page 57.
See “Dirty region logging in cluster environments” on page 448.
Log subdisks are ignored as far as the usual plex policies are concerned, and are
only used to hold the dirty region log.
Warning: The version 20 DCO volume layout includes space for a DRL. Do not use
procedures that are intended for manipulating log subdisks with a volume that
has a version 20 DCO volume associated with it.
See “Preparing a volume for DRL and instant snapshots” on page 359.
277Creating and administering subdisks and plexes
Associating log subdisks