Oracle in a Nutshell

Backing up datafiles

You can make a user-managed consistent backup of your complete Oracle database after you have shut down the database with the NORMAL, IMMEDIATE, or TRANSACTIONAL keyword. Once the database is shut down, you use the appropriate operating system command to back up or copy the datafiles.

You can also back up individual tablespaces and datafiles. If a tablespace is offline, you can use the appropriate operating system command to back up the datafiles. If the tablespace is online, you must first put the tablespace into BACKUP mode by issuing the following command in SQL*Plus:

ALTER TABLESPACE tablespace_name BEGIN BACKUP;

Once the backup is complete, you issue either of the following commands:

ALTER TABLESPACE tablespace_name END BACKUP;
ALTER DATABASE END BACKUP;

to return to normal operation. Because there is extra overhead involved in writing the extra information to the log files while in BACKUP mode, you should always end the mode as soon as your backup completes successfully.

Tip

You may need to use the ALTER DATABASE END BACKUP command if your database is still in BACKUP mode when it fails. Oracle will not reopen a tablespace in BACKUP mode, so you will need to mount the database, run this command, and then open the database.

You may find that it makes more sense to back up your tablespaces serially, rather than in a single job. By backing up your tablespaces one at a time, you avoid having to put all the tablespaces in BACKUP mode for the duration of the complete ...