How to apply an interim patch in RAC database .

we can follow the following practice to apply an interim patch(one- off patch ) in RAC database .

1.Before applying  the interim patch in RAC nodes , first take the backup of ORACLE_HOME in each database nodes through tar command .

As root/oracle user take the backup of oracle home that we intend to patch 

#tar -cvzf /bkp_location/oracle_12.1.0.2.tar.gz  /u01/app/oracle/product/12.1.0.2/

 To appy patch we need to login as  oracle user 

2.If the patch is a rolling one ,we can apply the patch either through local mode or in rolling patch mode.
How to check the patch is a rolling one  ?

[oracle@pdc01]$ $ORACLE_HOME/OPatch/opatch query -is_rolling_patch /nfs1/BINARIES/DB_Patch/p20476175_121020_Linux-x86-64.zip
Oracle Interim Patch Installer version 12.1.0.1.8
Copyright (c) 2015, Oracle Corporation.  All rights reserved.
Oracle Home       : /u01/app/oracle/product/12.1.0.2/db_1
Central Inventory : /u01/app/aoraInventory
   from           : /u01/app/oracle/product/12.1.0.2/db_1/oraInst.loc
OPatch version    : 12.1.0.1.8
OUI version       : 12.1.0.2.0
Log file location : /u01/app/oracle/product/12.1.0.2/db_1/cfgtoollogs/opatch/opatch2015-11-12_11-32-12AM_1.log
--------------------------------------------------------------------------------
 Patch is a rolling patch: true
 Patch is a FMW rolling patch: false
OPatch succeeded.
[oracle@pdc01]$
Or you can test it by following method,

3.Unzip the patch and go to patch directory

[oracle@pdc01]$unzip /nfs1/BINARIES/DB_Patch/p20476175_121020_Linux-x86-64.zip
[oracle@pdc01 20476175]$ /u01/app/oracle/product/12.1.0.2/db_1/OPatch/opatch query -all | grep -i "Need to shutdown Oracle instances"
 Need to shutdown Oracle instances: true
[oracle@pdc01 20476175]$
[oracle@pdc01 20476175]$ /u01/app/oracle/product/12.1.0.2/db_1/OPatch/opatch query -all | grep -i "Patch is a rolling patch"
 Patch is a rolling patch: true
[oracle@pdc01 20476175]$

4.Shut down all the services running from the Oracle home of the database of Oracle Database home. - please see the readme file for more information.

5.Apply the interim patch (one-off patch )
choose one of the following method to apply interim patches in RAC environment.

5.1   -local
              Patch the local node, then update inventory of the
              local node. Do not propagate the patch or inventory
              update to other nodes.

[oracle@pdc01 20476175]$/u01/app/oracle/product/12.1.0.2/db_1/OPatch/opatch apply -local 

Repeat the steps in remaining nodes .
 

5.2 -all_nodes (Default)
            if you don't specify -local along with opatch apply  then opatch will  patch node 1 first , once it finish with node1 , opatch will list the remaining nodes to patch . At this point we can select the remaining nodes and opatch will continue patching with remaining nodes .

[oracle@pdc01 20476175]$/u01/app/oracle/product/12.1.0.2/db_1/OPatch/opatch apply