In the last article, we performed downgrade of Oracle RAC Database from 12c to 11gR2In this article, we are going to downgrade Oracle Grid Infrastructure from 12c ( to 11gR2 ( which contains two nodes ( node 1 & node 2).

Before doing CRS downgrade we need to take backup of following files :

  • Take tar backup of $ORA_CRS_HOME from both nodes.
  • Take tar backup of ORAINVENTORY from both nodes.
  • Take voting disk backup from one node. In 11gR2, your voting disk data is automatically backed up in the OCR
  • Take a backup of init.d folder in /etc folder on both nodes.

Firstly, perform prechecks on existing Grid Home

To begin the downgrade run the with downgrade option on all but the OCR-node. In this case, the node1 is the OCR-node and downgrade first run on node2. It means we need to execute the following command as root from non-master node with cluster home.

How to Find Master Node.

Since this is a two node RAC the downgrade command is run with a lastnode option on node1 (OCR-node). This will remove the GI management repository, downgrade the OCR

Before starting the cluster with 11.2 update the inventory by setting crs=true for 11.2 GI home. At this point 12.1 GI home will have crs=true.

Run the following to update the inventory

Verify the inventory update

Start the CRS on all nodes.

This concludes the steps to successfully downgrading GI from to

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    One more way to find the lastnode.

    cd /opt/oracle/product/


    ls -lrt
    total 266508

    -rw——-. 1 root root 130663 Sep 6 11:56 ocr11. – check for similar file on both new grid home.

    with this we can conclude this is the last node.

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