Removing a NODE from RAC

1. Delete the instance on the node to be removed
2. Clean up ASM
3. Remove the listener from the node to be removed
4. Remove the node from the database
5. Remove the node from the clusterware

You can delete the instance by using the database creation assistant (DBCA), invoke the program choose the RAC database, choose instance management and then choose delete instance, enter the sysdba user and password then choose the instance to delete.

To clean up ASM follow the below steps

1. From node 1 run the below command to stop ASM on the node to be removed
   
     srvctl stop asm -n rac3
     srvctl remove asm -n rac3
2. Now run the following on the node to be removed
   
     cd $ORACLE_HOME/admin
     rm -rf +ASM
     cd $ORACLE_HOME/dbs
     rm -f *ASM*
3. Check that /etc/oratab file has no ASM entries, if so remove them

Now remove the listener for the node to be removed

·         Login as user oracle, and set your DISPLAY environment variable, then start the Network Configuration Assistant
     $ORACLE_HOME/bin/netca

·         Choose cluster management

·         Choose listener

·         Choose Remove

·         Choose the  name as LISTENER

Next we remove the node from the database

1. Run the below script from the node to be removed
   
   cd $ORACLE_HOME/bin
   ./runInstaller -updateNodeList ORACLE_HOME=$ORACLE_HOME "CLUSTER_NODES={rac3}" -local
   ./runInstaller
2. Choose to deinstall products and select the dbhome
3. Run the following from node 1
   
     cd $ORACLE_HOME/oui/bin
     ./runInstaller -updateNodeList ORACLE_HOME=$ORACLE_HOME "CLUSTER_NODES={rac1,rac2,rac3}"

Lastly we remove the clusterware software

1. Run the following from node 1, you obtain the port number from remoteport section in the ons.config file in $ORA_CRS_HOME/opmn/conf 
     $CRS_HOME/bin/racgons remove_config rac3:6200
2. Run the following from the node to be removed as user root
     cd $CRS_HOME/install
     ./rootdelete.sh
3. Now run the following from node 1 as user root, obtain the node number first 
     $CRS_HOME/bin/olsnodes -n
     cd $CRS_HOME/install
     ./rootdeletenode.sh rac3,3
4. Now run the below from the node to be removed as user oracle
   
      cd $CRS_HOME/oui/bin
     ./runInstaller -updateNodeList ORACLE_HOME=$ORACLE_HOME "CLUSTER_NODES={rac3}" CRS=TRUE -local
     ./runInstaller
5. Choose to deinstall software and remove the CRS_HOME
6. Run the following from node as user oracle
   
     cd $CRS_HOME/oui/bin 
     ./runInstaller -updateNodeList ORACLE_HOME=$ORACLE_HOME "CLUSTER_NODES={rac1,rac2,rac3}" CRS=TRUE
7. Check that the node has been removed, the first should report "invalid node", the second you should not see any output and the last command you should only see nodes rac1 and rac2 
   
     srvctl status nodeapps -n rac3
     crs_stat |grep -i rac3
     olsnodes -n