Overview of Database Backup and Recovery

The focus in Oracle Database backup and recovery is on the physical backup of database files, which permit you to reconstruct your database. The files protected by the backup and recovery facilities built into Oracle Enterprise Manager Database Control (Database Control) include datafiles, control files, server parameter files, and archived redo logs. With these files you can reconstruct your database. The backup mechanisms work at the physical level to protect against file damage, such as the accidental deletion of a datafile or the failure of a disk drive.

Oracle Recovery Manager (RMAN), a command-line and Enterprise Manager-based tool, is the Oracle-preferred method for efficiently backing up and recovering your Oracle database. RMAN is designed to work intimately with the server, providing block-level corruption detection during backup and restore. RMAN optimizes performance and space consumption during backup with file multiplexing and backup set compression, and integrates with leading tape and storage media products.

Logical-level backups, such as exporting database objects such as tables or tablespaces, are a useful supplement to physical backups, but cannot protect your whole database. An effective backup strategy must be based on physical-level backups.

The Oracle Database Flashback features provide a range of physical and logical data recovery tools as efficient, easy-to-use alternatives to physical and logical backups. The Flashback features enable you to reverse the effects of unwanted database changes without restoring datafiles from backup or performing media recovery.

This section introduces the following flashback features:

• Oracle Flashback Table, which enables you to revert a table to its contents at a time in the recent past

• Oracle Flashback Drop, which enables you to retrieve dropped database tables

• Oracle Flashback Database, which enables you to revert the entire database to a past point in time

The first two features operate at the logical level, whereas the last feature operates at the physical level. None of the preceding features requires advance preparation such as creating logical-level exports to allow for retrieval of your lost data. You can use all of the features while your database is available. Oracle Database Backup and Recovery User's Guide discusses the Flashback features of Oracle Database at greater length.

The Oracle Enterprise Manager physical backup and recovery features are built on the Recovery Manager (RMAN) command-line client. Database Control makes available many of the RMAN features, and provides wizards and automatic strategies to simplify and further automate RMAN-based backup and recovery.