What is a media recovery?

What is a media recovery?

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Media recovery is performed to recover a database, tablespace, data file, or set of blocks within a data file after a media failure damages some or all of the database files (data files, control files, or online redo log files). Media recovery involves the application of redo data (data stored in archived and online redo logs) or incremental backups to a restored backup in order to bring it to a specified state prior to the media failure. While performing a media recovery, if all redo data is applied to the restored backup, it is called complete recovery. If part of the redo data is applied, it is called incomplete recovery.

If a database is running in ARCHIVELOG mode, the database administrator can perform complete recovery or incomplete recovery to recover from a media failure. However, if the database is running in NOARCHIVELOG mode, the only option is to restore the most recent backup of the database, losing all data entered in the database after the last backup was taken. This is because, in NOARCHIVELOG mode, there is no archived redo data that can be applied to the restored backup of the database to bring it to a state prior to the media failure.

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