Advantage over tradition backup system:

1). copies only the filled blocks i.e. even if 1000 blocks is allocated to datafile but 500 are filled with data then RMAN will only create a backup for that 500 filled blocks.

2). incremental and accumulative backup.

3). catalog and no catalog option.

4). detection of corrupted blocks during backup;

5). can create and store the backup and recover scripts.

6). increase performance through automatic parallelization( allocating channels), less redo generation.