VERITAS Storage Foundation 4.1 Oracle Administrator's Guide

How VERITAS Database FlashSnap Works Prerelease 8 September 2005, 8:55am
200 VERITAS Storage Foundation for Oracle Administrator’s Guide
specifies snapshot options that will be used when creating a snapshot image (such as whether the
snapshot mode will be online, offline, or instant). For further details, see “Creating a
Snapplan (dbed_vmchecksnap)” on page 222.
After creating the snapplan, the database administrator must validate it to ensure that it is correct.
During validation the snapplan is copied to the repository before using it to create a snapshot.
Depending on the validation results, the database administrator may need to modify the snapplan or
the system administrator may need to adjust the storage configuration.
After storage is configured as specified in the snapplan and the snapplan has been validated, the
database administrator can create snapshots of the database and create database clones based on the
snapshots on either the same host or a secondary one.
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. Refer to the VERITAS Volume Manager 4.1 User’s Guide for details about
the Volume Manager FastResync.
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.
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. dbed_vmchecksnap is also used on the
secondary host to list the snapplan.
◆ 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.
◆ dbed_vmclonedb (used on the primary or secondary host)