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A backup is a full or partial copy of the information in a database, held in a physically separate location. If the database becomes unavailable, you can restore it from the backup. You can use your backups to restore all committed changes to the database up to the time it became unavailable.

Backing up a running database provides a snapshot of the database where the data is in a consistent state, even though other users are modifying the database.

If the operating system or database server fails, or the database server does not shut down properly, then the database must be recovered. On database startup, the database server checks whether the database was shut down cleanly at the end of the previous session. If it was not, the database server runs an automatic recovery process to restore all changes up to the most recently committed transaction.


In this section:
    Backing up Databases
    When you make a backup, decide where you want to store the backup files: on the database server computer or on the client computer.
    Types of Backup
    There are many choices to make when deciding when, where, and how to perform a backup. The decisions you make define the backup type to perform (for example, server-side and client-side, full and incremental).
    Backup Formats
    You should use an archive backup if you are backing up directly to tape. Otherwise, an image backup should be used because image backups are easier to restore.
    Backup and Recovery Restrictions
    The database server prevents certain operations from being executed while a backup is in progress.
    Server-Side Backups
    Making a backup on the database server computer is generally faster than a backup on a client computer because the data does not have to be transported across the client/server communications system.
    Backup Validation
    As part of your backup and recovery plan, you should periodically check that your database is valid by using tools such as the Validation utility (dbvalid).
    Database Recovery
    Recovery is the process of restoring your database file, transaction log, and dbspaces, and bringing the database file as up-to-date as possible with incremental transaction log files.
    Backup and Recovery Plan Design
    It is recommended that you develop and implement a backup schedule to protect your data. You should also ensure that you have created and tested your backup and recovery commands as part of your backup and recovery plan.