Media Management

Oracle's Media Management Layer (MML) API lets third-party vendors build a media manager, software that works with RMAN and the vendor's hardware to allow backups to sequential media devices such as tape drives. The media manager handles loading, unloading and labeling of sequential media such as tapes. You must install media manager software to use RMAN with sequential media devices.

When backing up or restoring, the RMAN client connects to the target instance and directs the instance to send requests to its media manager. No direct communication occurs between the RMAN client and media manager.

Performing Backup and Restore with a Media Manager

Before performing backup or restore to a media manager, you must allocate one or more channels to handle the commuication with the media manager. You can also configure default channels for use with the media manager, which will be applied for all backup and recovery tasks that use the media manager where you do not explicitly allocate channels. For a conceptual overview of channels, see "About RMAN Channels". Configuring or allocating channels for backups is discussed further in "Configuring and Allocating Channels for Use in Backups".

For example, this sequence of commands would configure channels for the media manager and back up the database to the media manager:

RMAN> CONFIGURE DEVICE TYPE sbt PARALLELISM 1;
RMAN> CONFIGURE DEFAULT DEVICE TYPE TO sbt;
RMAN> CONFIGURE CHANNEL DEVICE TYPE sbt PARMS 'ENV=(NSR_SERVER=bksvr1)';
RMAN> BACKUP DATABASE;

When RMAN executes the BACKUP DATABASE command, it sends the backup request to the database server session performing the backup. The database server session identifies the output channel as a media management device and makes a request to the media manager to write the output.

RMAN does not issue specific commands to load, label, or unload tapes. When backing up, RMAN gives the media manager a stream of bytes and associates a unique name with that stream. When RMAN needs to restore the backup, it asks the media manager to retrieve the byte stream. All details of how and where that stream is stored are handled entirely by the media manager.

The media manager labels and keeps track of the tape and names of files on each tape, and automatically loads and unloads tapes, or signals an operator to do so.

Some media managers support proxy copy functionality, in which they handle the entire data movement between datafiles and the backup devices. Such products may use technologies such as high-speed connections between storage and media subsystems to reduce load on the primary database server. RMAN provides a list of files requiring backup or restore to the media manager, which in turn makes all decisions regarding how and when to move the data.

Backup Solutions Program

The Oracle Backup Solutions Program (BSP), part of the Oracle Partner Program, is a group of leading media manager vendors whose products are compliant with Oracle's MML specification. Several products may be available for your platform from media management vendors. For more information, you can contact your Oracle representative for a list of available products, contact individual vendors to ask them if they participate, or access the Backup Solutions Program Web site at:

http://www.oracle.com/technology/deploy/availability

Note that Oracle does not certify media manager vendors for compatibility with RMAN. Questions about availability, version compatibility, and functionality can only be answered by the media manager vendor, not Oracle.