Veritas Storage Foundation Intelligent Storage Provisioning 5.0 Solutions Guide, HP-UX 11i v3, First Edition, May 2008

28 Off-host processing solutions
Implementing off-host processing solutions
The following sections describe how you can apply off-host processing to
implement regular online backup of a volume in a private disk group, and to set
up a replica of a production database for decision support. Two applications are
outlined:
■ Implementing off-host online backup
■ Implementing decision support
These applications use the Persistent FastResync feature of VxVM in
conjunction with linked break-off snapshots.
Implementing off-host online backup
This section describes a procedure for implementing off-host online backup for
a volume in a private disk group. The intention is to present an outline of how to
set up a regular backup cycle by combining the Persistent FastResync and linked
break-off snapshot features of VxVM. It is beyond the scope of this guide to
describe how to configure a database to use this procedure, or how to perform
the backup itself.
To back up a volume in a private disk group
1 On the primary host, create a new volume, snapvol, in a separate disk group,
snapvoldg, for use as the snapshot volume. This volume must be the same
size as the original volume, but it can differ in its layout and other
characteristics, such as the quality of storage. It is recommended that the
snapshot disk group contains storage that is dedicated to off-host
processing.
2 On the primary host, link the snapshot volume in the snapshot disk group to
the data volume:
# vxsnap -g volumedg -b addmir volume mirvol= snapvol \
mirdg=
snapvoldg
You can use the vxsnap snapwait command to wait for synchronization of a
linked snapshot volume to complete:
# vxsnap -g volumedg snapwait volume mirvol= snapvol \
mirdg=
snapvoldg
This step sets up the snapshot volumes, and starts tracking changes to the
original volumes. When you are ready to create a backup, proceed to step 3.
3 On the primary host, suspend updates to the volume that contains the
database tables. The database may have a hot backup mode that allows you
to do this by temporarily suspending writes to its tables. For example, Oracle
supports online backup by temporarily suspending updates to the datafiles
of the tablespaces, provided that the database is running in archive mode
and the tablespaces are online. As the Oracle database administrator, put
each tablespace into hot backup mode.