RMAN has the ability to back up at the database level (as shown in the prior section), the tablespace level, or, even more granularly, at the data file level. When you back up a tablespace, RMAN backs up any data files associated with the tablespaces(s) that you specify. For instance, the following command will back up all the data files associated with the SYSTEM and SYSAUX tablespaces:
RMAN> backup tablespace system, sysaux;
One scenario in which I back up at the tablespace level is if I’ve recently created a new tablespace and want to take a backup of just the data files associated with the newly added tablespace. Note that when B&R issues, it’s often more efficient to work with one tablespace (because it’s generally much faster to back up one tablespace than the entire database).