Home  >  Oracle Database Administration (DBA)  >  RAC  >  Oracle RAC Clusterware: OCR file & Voting disk

Oracle Clusterware includes the following processes:

1) Oracle Cluster Registry (OCR)

     - this is the central repository for the Oracle cluster: there we find all the information about the cluster in real-time;

     - CRS update the OCR with the information about the node failure or reconfiguration;

     - CSS update the OCR when a node is added or deleted;

     - NetCA, DBCA, SRVCTL update the OCR with the services information;

     - this is a binary file and cannot be edited;

     - the OCR information is cached on each node;

     - only one node (the master node) can update the OCR file => The master node has the OCR cache up-to-date in real time;

     - OCR file is automatically backed up in the OCR location every 4 hours:

           cd $CRS_HOME/cdata/<cluster name>

         ls
         backup00.ocr backup01.ocr backup02.ocr day.ocr day_.ocr week.ocr

     - OCR file can be backud up manually as well running the following command:

                  dd if=voting_disk_name of=backup_file_name

     - the OCR files are backed up for a week and overwritten in a circulary manner;

     - because the OCR is a key component of the Oracle cluster, the OCR file must be mirrored;

     - the OCR file can be exported, imported with ocrconfig command;    

More information about  this subject ( Oracle RAC Clusterware: OCR file & Voting disk ) you can get from  www.in-oracle.com