Restoring Incremental Backups with RMAN 
Restoring Incremental Backups with RMAN
Use
Any backups made with RMAN must also be restored with RMAN. This does not apply to backups made to disk. As of Release 4.5A SAPDBA supports a database reset to an incremental backup. As of Release 4.5B, SAPDBA also supports a partial restoration followed by a recovery using incremental backups. You can continue to recover the database by importing the offline redo log files if you want.
Prerequisites
In contrast to the BRRESTORE restoration process (without RMAN) where the database has to be closed, a restoration with RMAN needs the database to be mounted. A restoration for the incremental backup strategies consists of several steps.
Features
The procedure for resetting the entire database to an incremental backup, or to a point in time before the database failure (database reset, point-in-time recovery, disaster recovery) is as follows:
1.) Prerequisite: The database is closed.
Restoration of the control file and, if needed, the online redo log files with BRRESTORE (without RMAN) from the last incremental backup.
2.) Prerequisite: The database is mounted.
Restoration of the full backup (level 0) (with RMAN).
Restoration of the last incremental backup (with RMAN), possible rest point.
3.) Prerequisite: The database is mounted.
Import the offline redo log files into the database to reset the data to the required point in time.
If only some of the files are corrupt (partial restore and full recovery), perhaps due to a media error, then you only need to restore those files from the full backup and then restore the last incremental backup. RMAN then makes the changes to the files automatically, restoring them to the last incremental backup. The current database is recovered by restoring the redo log files.
If the database has been restored since the last full backup (level 0), then you cannot use it as a reference for the next incremental backup.