Backing Up the Control File

Because control files record the physical structure of the database, always make a backup of the control file immediately after making any changes to the physical structure of the database. You can create a backup of the control files at any time the database is operational; however, you cannot restore a control file from a backup without the full contingent of the associated data files. This is because the control file is a living and growing file that corresponds exactly to the database's status at that particular point in time.

As long as you have the data files stated in the control file, you can restore the control file safely.

There are two different ways to create a backup of the control file. You can either back up the control file to a specific filename, or you can back it up to trace.

The following command allows you to back up the control file to the given file's name:

 ALTER DATBASE BACKUP CONTROLFILE TO 'filename' 

You can also back up the control file to a trace file as follows:

 ALTER DATABASE BACKUP CONTROL FILE TO TRACE 

This creates a file with the .trc extension in the user dump destination directory that contains the SQL required to re-create your control file.

Further information on backing up and recovery of the control files is explored in detail in preparation for the Oracle 9i DBA Fundamentals II test.