To store backups on tape, RMAN requires media manager software, a third party software program that writes, reads, and manages sequential media such as tapes to backup and recover data. In the case of backup, RMAN starts the Oracle Server session which reads data and sends it to the media manager which writes the data to the tape device. In the case of restore, the media manager software reads the data from the tape and sends it to the Oracle Server session which restores data to the disk.
The SBT API is the interface through which RMAN interacts with the media manager. The API defines the functions that create backup files, write to/read from the backup media, and search for/remove backup files. Management of backup devices and media is handled by the media manager, and is outside the scope of the SBT API.
The core of the RMAN and media manager software integration is the media management library, supplied by the backup vendor. This library contains an implementation of the SBT API functions, and is linked in with the Oracle server binary. In Oracle 8.1.6 and below versions, the library must be explicitly linked in with the Oracle server binary before starting RMAN. In Oracle 8.1.7, the library is implicitly loaded by the OS on the start of the Oracle server session. In Oracle9i and 10g, the library is automatically loaded when RMAN channels are allocated.Oracle calls these SBT functions to back up and restore data files to and from media controlled by the media manager.
The commom media manager software with RMAN are