Oracle Cluster Registry and Voting Disks

OCR and voting disks are shared files on a cluster filesystem. OCR contains the configuration information about the cluster resources. Voting Disks are used to monitor cluster node status. 

To display OCR locations
$ ocrcheck 
To replace the current OCR location
# ocrconfig -replace <current_location> -replacement <new_location>
To add new OCR location. Create empty file first with touch command.
# ocrconfig -add <new_location>
To delete OCR location. If only one OCR location configured and online, it cannot be deleted.
# ocrconfig -delete <current_location>

To retrieve the list of voting files.
$ crsctl query css votedisk 
To add a voting disk
$ crsctl add css votedisk <new_location>
To delete a voting disk. If only one vote disk configured and online, it cannot be deleted.
$ crsctl delete votedisk <Universal_File_Id>
If all voting disks are lost, start css in exclusive mode and replace voting disk.
# crsctl start crs -excl
# crsctl replace votedisk <location>

In Oracle Clusterware 11gR2, the voting disk data is automatically backed up in OCR as part of any configuration change and is automatically restored to any voting disk added. The CRSD process automatically creates the OCR backup every four hours in $GRID_HOME/cdata/<cluster_name>.

To list the backup files
$ ocrconfig -showbackup
To restore OCR backup. Stop clusterware on all nodes. Create empty OCR file with same name if the original file doesn't exist.
# ocrconfig -restore <backup_location>

To verify Clusterware version
$ crsctl query crs activeversion
To verify clusterware running on the node
$ crsctl check crs