Backup Type

Backups are divided into physical backups and logical backups:

  • Physical backups are backups of the physical files used in storing and recovering your database, such as data files, control files, and archived redo logs. Ultimately, every physical backup is a copy of files storing database information to some other location, whether on disk or offline storage, such as tape.

  • Logical backups contain logical data (for example, tables or stored procedures) extracted from a database with Oracle Data Pump (export/import) utilities. The data is stored in a binary file that can be imported into Oracle Database.

Physical backups are the foundation of any backup and recovery strategy. Logical backups are a useful supplement to physical backups in many circumstances but are not sufficient protection against data loss without physical backups.

Reconstructing the contents of all or part of a database from a backup typically involves two phases: retrieving a copy of the data file from a backup, and reapplying changes to the file since the backup, from the archived and online redo logs, to bring the database to the desired recovery point in time. To restore a data file or control file from backup is to retrieve the file from the backup location on tape, disk, or other media, and make it available to Oracle Database. To recover a data file, is to take a restored copy of the data file and apply to it the changes recorded in the database's redo logs. To recover a whole database is to perform recovery on each of its data files.