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

add the site to the disk group fails. If the -f option is specified, the command
does not fail, but instead it sets the allsites attribute for the volume to off.
Note: By default, volumes created will be mirrored when sites are configured in
a disk group. Initial synchronization occurs between mirrors. Depending on the
size of the volume, synchronization may take a long time. If you do not need to
perform an initial synchronization across mirrors, use init=active with the
vxassist command.
About site consistency
Site consistency means that at any point in time, the data at each site is consistent
with the application for a given set of volumes. A site-consistent volume must
have at least one plex, or mirror, on each configured site in the disk group. The
site consistency is ensured by detaching a site when a site-consistent volume loses
its last complete plex on that site. The site detach detaches all the plexes on that
site and also disallows further configuration updates to the configuration copies
on that site. Turn on this behavior by setting the siteconsistent attribute to on
on the desired volumes.
If you set the siteconsistent attribute to off, only the plex that fails is detached.
The plexes for the remaining volumes on that site are not detached.
The siteconsistent attribute is also present at the disk group level and can be
used to turn on or off the site consistency functionality in the disk group boundary.
In addition, if you turn on the siteconsistent attribute for a disk group, each
new volume created in the disk group inherits the site consistency of the disk
group, by default. Setting the siteconsistent attribute on a disk group does not
affect siteconsistent attributes for existing volumes. You can also control the
site consistency on individual volumes.
By default, a volume inherits the value that is set on its disk group.
By default, creating a site-consistent volume also creates an associated version
20 DCO volume, and enables Persistent FastResync on the volume. This allows
faster recovery of the volume during the reattachment of a site.
See “Configuring site consistency on a volume” on page 477.
Before setting site consistency on a disk group, be sure to meet the following
requirements:
■ A license enabling the Site Awareness feature must be purchased for each host
in the Remote Mirror configuration.
469Administering sites and remote mirrors
About sites and remote mirrors