When a media loss occurs it can hit either critical or non-critical data files or a combination of both. In the event of media loss several Oracle storage structures may be compromised, this includes redo log files, control files and temporary files also. Non critical database files are all database file except those that belong to the SYSTEM, SYSAUX, and UNDO tablespaces. The critical data files are those that belong to the SYSTEM, SYSAUX, and UNDO tablespaces. The procedure to recover from a loss of datafiles, either critical or non-critical is quite the same, the difference comes after the database possibility to be open with the damaged data files offline and perform the recovery process when the database is open.