About the RMAN Environment

Recovery Manager (RMAN) is a client application that performs backup and recovery operations. The Recovery Manager environment consists of the various applications and databases that play a role in a backup and recovery strategy.

Table 1-1 lists possible components of the RMAN environment.

Table 1-1 Components of the RMAN Environment

Component	Description	Required?
Target database	The control files, datafiles, and optional archived redo logs that RMAN is in charge of backing up or restoring. RMAN uses the target database control file to gather metadata about the target database and to store information about its own operations. The work of backup and recovery is performed by server sessions running on the target database.	Yes
RMAN client	The client application that manages backup and recovery operations for a target database. The RMAN client can use Oracle Net to connect to a target database, so it can be located on any host that is connected to the target host through Oracle Net.	Yes
Recovery catalog database	A database containing the recovery catalog schema, which contains the metadata that RMAN uses to perform its backup and recovery operations.	No
Recovery catalog schema	The user within the recovery catalog database that owns the metadata tables maintained by RMAN. RMAN periodically propagates metadata from the target database control file into the recovery catalog.	No
Standby database	A copy of the primary database that is updated using archived logs created by the primary database. RMAN can create or back up a standby database. You can fail over to the standby database if the primary database goes down.	No
Duplicate database	A copy of the primary database that you can use for testing purposes.	No
Media management application	A vendor-specific application that allows RMAN to back up to a storage system such as tape.	No
Media management catalog	A vendor-specific repository of information about a media management application.	No
Enterprise Manager	A browser-based interface to the database, including backup and recovery through RMAN.	No

The only required components in an RMAN environment are the target database and the RMAN client, but most real-world configurations are more complicated. One might use an RMAN client connecting to multiple media managers and multiple target, recovery catalog, and auxiliary databases, all accessed through Enterprise Manager.

RMAN Session Architecture

The RMAN client application directs database server sessions to perform all backup and recovery tasks. The meaning of "session" in this sense depends on the operating system. For example, on UNIX, a server session corresponds to a server process, while on Windows it corresponds to a thread within the database service.

The RMAN client itself does not perform backup, restore, or recovery operations. When you connect the RMAN client to a target database, RMAN allocates server sessions on the target instance and directs them to perform the operations. The RMAN client uses internal, undocumented PL/SQL packages to communicate with the target database and recovery catalog.