Oracle Backup:Basic concepts
A backup is a copy of data. This copy can include important parts of the database such as the control file and datafiles. A backup is a safeguard against unexpected data loss and application errors. If you lose the original data, then you can reconstruct it by using a backup.
Backups are divided into physical backups and logical backups. Physical backups, which are the primary concern in a backup and recovery strategy, are copies of physical database files. You can make physical backups with either the Recovery Manager (RMAN) utility or operating system utilities. In contrast, logical backups contain logical data (for example, tables and stored procedures) extracted with the Oracle Export utility and stored in a binary file. You can use logical backups to supplement physical backups.
physical backups
Physical database files that have been copied from one place to another. The files can be datafiles, archived redo logs, or control files. You can make physical backups using Recovery Manager or with operating system commands such as the UNIX cp.
logical backups
Backups in which the Export utility uses SQL to read database data and then export it into a binary file at the operating system level. You can then import the data back into a database using the Import utility.
Backups taken with the Export utility differ in the following ways from RMAN backups:
- Database logical objects are exported independently of the files that contain those objects.
- Logical backups can be imported into a different database, even on a different platform. RMAN backups are not portable between databases or platforms.