In the last article, we performed downgrade of Oracle Standalone Database from 12c to 11gR2. In this article, we can downgrade the 2 node RAC 12.1.0.2 database to 11.2.0.4, downgraded the database only and not the grid home.

Assume all commands are being run on node 1, any commands that need to be run on node 2 will be explicitly stated.

Initially set ORACLE_HOME to current 12.1.0.2 environment.

1. Stop database using srvctl on from 1st node

2. Create pfile from spfile

3. edit pfile CLUSTER_DATABASE parameter to FALSE

4. Recreate spfile with new parameter

5. Startup database in downgrade mode using new spfile

6. Execute Oracle downgrade script from the 12.1.0.2 Oracle Home.

7. Change environment variables and restore config files. Execute these steps on both nodes.

Note: Copy password files and config files from current ORACLE_HOME to a downgraded directory. Also, change the entry in ORATAB file on all nodes.

8. After that start to upgrade mode, execute the catrelod script from the downgraded version $ORACLE_HOME/rdbms/admin directory.

9. Now execute utlrp.sql script Recompile all existing PL/SQL modules in the INVALID state. Also set CLUSTER_DATABASE parameter to TRUE  and Shutdown the database.

10. Downgrade cluster services,Now we need to change database configuration in the cluster to our old ORACLE_HOME and version

SYNTAX

in our case this was the following:

Please start database once and stop again for confirmation :

Here our Database down gradation completed successfully.

Stay Tuned for Downgrade the Oracle Grid Infrastructure.

Thank you for giving your valuable time to read the above information.

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