How to restore or recreate the OLR if you don't have backup

 

The steps you shared are typically used for deconfiguring and reconfiguring Oracle Clusterware in an Oracle Real Application Clusters (RAC) environment, especially for recreating the Oracle Local Registry (OLR) file. 

Here's an explanation of the commands:

1. Stop Clusterware

   # crsctl stop crs -f

   • This command stops the Oracle Clusterware stack on the local node forcefully.
   • The -f option ensures that all services are stopped even if there are dependencies.

2. Deconfigure Clusterware

   # $GRID_HOME/crs/install/rootcrs.pl -deconfig -force

   • This Perl script is used to deconfigure Oracle Clusterware.
   • The -deconfig flag removes the cluster configuration from the node.
   • The -force flag ensures that the operation proceeds even if warnings are encountered.

3. Recreate OLR

   # $GRID_HOME/root.sh

   • The root.sh script is executed to recreate the OLR and reinitialize the node with the Oracle Clusterware configuration.

Important Considerations

• Always ensure you have a valid backup of the OLR and any other critical Clusterware files before proceeding with these steps.
• Use these steps only under the guidance of Oracle Support or when you are certain about the procedure, as they involve low-level configuration changes.
• If the RAC setup involves multiple nodes, ensure proper coordination across all nodes for any deconfiguration or reconfiguration.