Backing Up the Control File

Backing Up the Control File

The control file is critical for recovery, as it contains crucial information like database checkpoints and the datafile header checkpoints for the datafiles. A recovery is much harder when you lose all copies of your control file. You also need to create a new control file when you want to change the name of a database, clone a database in a different location, or increase the maximum number of files you specified when you first created the control file.

You've seen how you can back up a control file using RMAN's BACKUP CONTROLFILE command. That command will produce a binary copy of the control file. You can also use the SQL statement ALTER DATABASE BACKUP CONTROLFILE from the SQL*Plus interface or from within RMAN to back up your control files.

It's a good practice to back up your control file on a regular basis by using the BACKUP CONTROLFILE TO TRACE command, as shown here:

SQL> ALTER DATABASE BACKUP CONTROLFILE TO TRACE;
Database altered.
SQL>

You can use the ALTER DATABASE BACKUP CONTROLFILE TO TRACE AS 'filename' command to achieve the same result as the preceding command. It will produce a text file that has the CREATE CONTROLFILE statement in it.

You should immediately back up your control file after you perform any of the following operations:

• Create or drop a tablespace.

• Add or rename a datafile.

• Add, rename, or drop an online redo log group or member.