Controlfile Multiplexing

Control file contains crucial database information and loss of this file will lead to loss of important data about database. So it is recommended to have multiplexed copies of files in different locations.

If control file is lost in 9i, database may go for force shutdown, where as database will continue to run, if it is 10g version and above.

Multiplexing Steps

Check if the database is running with spfile

SQL> show parameter spfile 

If yes, then check the control files

SQL> show parameter control_files 

Now add the new controlfile to below command along with old controlfiles from above command. We will add control03.ctl

SQL> alter system set control_files='/u02/prod/control01.ctl','/u02/prod/control02.ctl','/u02/prod/control03.ctl' scope=spfile; 

We need to bounce the database and copy control02.ctl as control03.ctl

SQL> shutdown immediate
SQL> ! cp /u02/prod/control01.ctl /u02/prod/control04.ctl 

Start the database

SQL> startup