Veritas Storage Foundation 5.1 SP1: Storage and Availability Management for Oracle (5900-1504, April 2011)

Online database snapshots
Table 10-1 describes the three types of snapshots that can be created.
Table 10-1
Database snapshot types
DescriptionDatabase
snapshot type
If the SNAPSHOT_MODE specified in the snapplan is set to online,
the dbed_vmsnap command first puts the tablespaces to be snapshot
into backup mode. After the snapshot is created, the tablespaces are
taken out of backup mode, the log files are switched to ensure that
the extra redo logs are archived, and a snapshot of the archive logs is
created.
Both online and offline snapshots provide a valid backup copy of the
database.
online
If the SNAPSHOT_MODE is set to offline, the database must be shut
down before the snapshot is created. Online redo logs and control files
are required and will be used to ensure a full database recovery.
offline
If the SNAPSHOT_MODE is set to instant, tablespaces are not put into
and out of backup mode. Online redo logs and control files are required
and will be used to ensure a full database recovery.
Instant snapshots do not represent a valid backup copy for
point-in-time recovery.
instant
Note: For Storage Foundation for Oracle RAC, only the online snapshot mode is
supported.
Database FlashSnap supports online database snapshot types.
When the SNAPSHOT_MODE specified in the snapplan is set to online, the
dbed_vmsnapcommand first puts the tablespaces to be snapshot into backup mode.
After the snapshot is created, the tablespaces are taken out of backup mode, the
log files are switched to ensure that the extra redo logs are archived, and a snapshot
of the archive logs is created.
Online snapshots provide a valid backup copy of the database.
Tasks before creating a snapshot
Review the details on how to create snapshots of all volumes on a database using
the snapplan.
147Using Database FlashSnap for backup and off-host processing
About creating database snapshots