How to Multiplex a Control File in Oracle

Multiplexing the control file in Oracle is a crucial practice to enhance the security and availability of your database. This step-by-step guide walks you through a hands-on approach to properly multiplex a control file in Oracle.

Step 1: Verify Existing Control Files

Before starting, identify the current control files used by your Oracle database:

SELECT name FROM v$controlfile;

Take note of the file paths for later reference.

Step 2: Copy the Control File to a New Location

Now, copy the existing control file to a new location. Suppose the current control file is located at +DATA/HIGOR/CONTROLFILE/, and we’ll copy it to /home/oracle/control.ctl:

cp +DATA/HIGOR/CONTROLFILE/current.279.1173307803 /home/oracle/control.ctl

Step 3: Generate a PFILE from the SPFILE

To edit the parameter file (PFILE), you first need to generate a PFILE from the current SPFILE. This will allow you to manually update the necessary configurations:

CREATE PFILE='/tmp/initPROD1.ora' FROM SPFILE;

Step 4: Edit the PFILE to Add the New Control File Path

Open the newly created PFILE (/tmp/initPROD1.ora) and add the path to the copied control file:

*.control_files='/home/oracle/control.ctl', '<existing_path_1>', '<existing_path_2>'

Replace <existing_path_1> and <existing_path_2> with the control file paths identified in Step 1.

Step 5: Start the Database Using the PFILE

Start your Oracle database using the edited PFILE:

STARTUP PFILE='/tmp/initPROD1.ora';

Step 6: Confirm Successful Multiplexing

Once the database starts, verify that the new control file has been multiplexed correctly:

SELECT name FROM v$controlfile;

Ensure the new control file path is listed along with the existing ones.

Step 7: Update the SPFILE with the PFILE Changes

Next, update the SPFILE with the changes you made in the PFILE:

CREATE SPFILE FROM PFILE='/tmp/initPROD1.ora';

Step 8: Restart the Database with the Updated SPFILE

Finally, restart the database using the updated SPFILE:

SHUTDOWN IMMEDIATE;
STARTUP;

Conclusion

This practical guide demonstrates how to multiplex a control file in Oracle, increasing the redundancy and resilience of your control file storage. Make sure to adjust file paths and configurations to match your Oracle environment.

Additional Tip

To check whether your Oracle instance is running with an SPFILE or PFILE, use the following query:

SHOW PARAMETER spfile;

• If the database is using an SPFILE, the full path to the SPFILE will be displayed.
• If it’s running with a PFILE, you’ll see a message indicating that no SPFILE is set.

By following these steps, you’re enhancing the reliability of your Oracle database through proper control file multiplexing.