Physical backups are copies of physical database files. For example, a physical backup might copy database content from a local disk drive to another secure location.
A physical backup can be hot or cold:
Hot backup—Users can modify the database during a hot backup. Log files of changes made during the backup are saved, and the logged changes are applied to synchronize the database and the backup copy. A hot backup is used when a full backup is needed and the service level does not allow system downtime for a cold backup.
Cold backup—Users cannot modify the database during a cold backup, so the database and the backup copy are always synchronized. Cold backup is used only when the service level allows for the required system downtime.
You can perform a full or incremental physical backup:
Note: | A cold full physical backup is recommended. |
Full—Creates a copy of data that can include parts of a database such as the control file, transaction files (redo logs), archive files, and data files. This backup type protects data from application error and safeguards against loss by providing a way to restore original data. Perform this backup weekly, or biweekly, depending on how often your data changes. Making full backups cold, so that users cannot make changes during the backups, is recommended.
Note: | The database must be in archive log mode for a full physical backup. |
Incremental—Captures only changes made after the last full physical backup. The files differ for databases, but the principle is that only transaction log files created since the last backup are archived. Incremental backup can be done hot, while the database is in use, but it slows database performance.
In addition to backups, consider using clustering or log shipping to secure database content. See the Oracle Hyperion Enterprise Performance Management System High Availability Guide and the RDBMS documentation.