Sunday, November 25, 2007

Administer the Oracle Cluster Registry

The OCR contains information about the cluster node list, which instances are running on which nodes, and information about Oracle Clusterware resource profiles for applications that have been modified to be managed by Oracle Clusterware.

In this post, I am going to discuss about how to Administer the OCR:

a)Adding an OCR Location
b)Replacing an OCR
c)Repairing an Oracle Cluster Registry Configuration on a Local Node
d)Removing an Oracle Cluster Registry

Note:ocrconfig command cannot modify OCR configuration information for nodes that are shut down or for nodes on which Oracle Clusterware is not running. So, you should avoid shutting down nodes while modifying the OCR using the ocrconfig command.

a)Adding an OCR Location

OCR location can be added after upgrade or after Installation of RAC. Oracle RAC environment do not support more then two OCR's (Primary and Secondary). In your enviornment if the the OCR is already mirror you do not require to add an OCR location. It is important to note that if you opted for normal redundancy instead of external redudancy,Oracle Clustware can manage two OCR's automatically.

Target location for additional OCR can be a desitnation_file or a disk.

ocrconfig -replace ocr destination_file
ocrconfig -replace ocr disk

To add a mirror OCR location

ocrconfig -replace ocrmirror destination_file
ocrconfig -replace ocrmirror disk

Note: Use above command as root user.

b)Replacing an OCR: You can change the location of an existing OCR or change the location of failed OCR to the location of working one. Follow the below steps as long as OCR file remains online.

1. verify that a copy of the OCR other than the one you are going to replace is online:


Note:The OCR that you are replacing can be either online or offline

2. Verfiy if the Oracle clusteware is running on the node where the replace operatoin will be performed.

crsctl check crs

3. Replace the OCR (using destination_file or disk)

ocrconfig -replace ocr destination_file
ocrconfig -replace ocr disk

4. To replace an OCR mirror location (using destination_file or disk)

5. To let that node rejoin the cluster after the node is restarted where the node was shutdown/stopped.

ocrconfig -repair

c)Repairing an Oracle Cluster Registry Configuration on a Local Node

To repair an OCR configuration on the node on which you have stopped the Oracle Clusterware daemon.

ocrconfig –repair ocrmirror device_name

Note:Node that was shut down while you were adding, replacing, or removing an OCR.You cannot perform this operation on a node on which the Oracle Clusterware daemon is running.This operation changes the OCR configuration only on the node from which you run this command.

d)Removing an Oracle Cluster Registry

Do not perform this OCR removal procedure unless there is at least one active OCR online

1. To ensure that at least one OCR other than the OCR that you are removing is online

2. To remove one copy of the OCR

ocrconfig -replace ocr

Note: Run the above command on any node in the cluster.It updates the OCR configuration on all the nodes on which Oracle Clusterware is running.


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Sridevi Koduru (Senior Oracle Apps Trainer
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