Veritas Storage Foundation™ for Oracle 5.0.1 Administrator's Guide

on any node on either the same host or a secondary one or on both nodes if used
within Oracle RAC..
A database clone can be used on a secondary host for off-host processing, including
decision-support analysis and reporting, application development and testing,
database backup, and logical error recovery. After a user has finished using the
clone on a secondary host, the database administrator can shut down the clone
and move the snapshot database back to the primary host. Regardless of whether
a snapshot is used on the primary or secondary host, it can be resynchronized
with the primary database using Database FlashSnap. Database FlashSnap utilizes
Veritas Volume Manager FastResync to quickly resynchronize the changed section
between the primary and snapshot.
Database FlashSnap can also be used to recover the primary copy of the database
if it becomes corrupted by overwriting it with the snapshot. You can recover the
primary database with a snapshot using the reverse resynchronization
functionality of Database FlashSnap. In an Oracle RAC configuration, reverse
resynchronization is not supported. Also in Oracle RAC, the dbed_vmsnap and
dbed_vmclonedb commands can be executed on the CVM master or slave node.
The dbed_vmchecksnap command can be executed at any node within the cluster.
See the Veritas Volume Manager User's Guide.
Database FlashSnap commands
The Database FlashSnap feature consists of three commands:
■ dbed_vmchecksnap (used on the primary host)
Creates and validates the snapshot plan used to create a snapshot image of an
Oracle database. You can also use dbed_vmchecksnap to copy, list, or remove
a snapplan or make sure the storage is configured properly for the task. The
dbed_vmchecksnap command is also used on the secondary host to list the
snapplan.
In Oracle RAC, this command can be used on any node within the RAC cluster
except when validating a snapplan, when dbed_vmchecksnap is run on the
CVM master or slave node.
■ dbed_vmsnap (used on the primary host)
Creates a snapshot image of an Oracle database by splitting the mirror volumes
used by the database. You can also use dbed_vmsnap to resynchronize snapshot
volumes with their original volumes. The command also allows you to
resynchronize the original volumes from the data in the snapshot volumes,
which is useful if the original volumes become corrupted. Resynchronizing
the original volumes from the snapshot volumes is known as reverse
resynchronization.
227Using Database FlashSnap for backup and off-host processing
About Veritas Database FlashSnap