Veritas Storage Foundation Intelligent Storage Provisioning 5.0.1 Administrators Guide, HP-UX 11i v3, First Edition, November 2009

This operation creates a temporary 2-way mirror volume that requires at least
two disks, and therefore twice as much disk space as the size of the temporary
volume. The size of the temporary volume is based on the size of the volume that
is being changed. If required, you can use the tmplen attribute to specify the size
of the temporary volume.
For example, the following command changes the stripe unit size of the volume
vol1 to 32 KB:
# vxassist -g mydg -b setstwidth vol1 stripeunit=32k
Adding logs to a volume
To add logs to a volume, use the following command:
# vxassist [-g diskgroup] [-b] addlog volume logtype=type \
[nlogs=number] [loglen=length] [attributes...]
The supported log types are dcm, dco, drl and raid5.
Adding a data change object (DCO) and DCO plex to a volume also allows the use
of instant snapshots and dirty region logging (DRL) with the volume.
Traditional DRL may be added by specifying logtype=drl instead of logtype=dco.
Such logs are implemented using a dedicated plex for each log copy, rather than
using a DCO volume, and are supported for mirrored volume layouts only.
Data change map (DCM) logs are used with Veritas Volume Replicator (VVR)
replicated volumes. This type of log is usually added automatically by VVR
administration commands.
RAID-5 logs are supported for software RAID-5 volumes only.
By default, one log or a DCO with one plex is added. You can use the nlogs attribute
to specify the number of logs or DCO plexes to add. The loglen attribute can be
used to specify the size of a RAID-5 log or a DCO volume. If the volume already
contains such a log or DCO volume, this attribute is ignored. For a DCO volume,
ISP may round up the length to make room for the maps that are required. For a
RAID-5 log, a minimum size of three times the full stripe width is imposed, and
the length is rounded up to a integral multiple of the full stripe width.
You can use storage attributes to specify the storage to be used for the logs.
For example, the following command adds a DCO plex to the volume, mirvol1,
using disk enc1_7:
# vxassist -g mydg -b addlog mirvol1 logtype=dco \
use_storage=’"DeviceName"="enc1_7"’
89Administering application volumes
Adding logs to a volume