Pankaj Chandiramani's Blog

Administring OCR
We will see how OCR(Oracle cluster Registry) backup & recovery is done .

Backup
Oracle clusterware automatically creastes a OCR backup every 4 hrs & retains the last 3 backups . Actually the CRSD process creates & manages the backup for each full day & a weekly backup at nd of the week .
Default backup Location : $CRS_HOME/cdata/$clustername

Other than the automated backup , you can export the content any time you want to a file .
eg : $ ocrconfig -export emergency_export.ocr

You can see the list of ocrbackup by using :
$ ocrconfig -showbackup

As the backup directory is default , you can change the dir by using below command
$  ocrconfig -backuploc <directory>

Restore
OCR can be restored (if you have a backup ) be below command

NOTE: Should you need to restore, make sure all CRS daemons on all nodes are stopped.

To perform a restore, execute the command:

$ cd CRS_Home/cdata/crscluster
$ ocrconfig -restore  week.ocr

If you had exported using the above command & want to resore , then you can use import
IMPORTANT: Importing a backup when CRS daemons are running will only corrupt OCR.  

$ ocrconfig -import emergency_export.ocr

If anything is wrong than you can use the OCRDUMP comand to dump all info to a file & check
$ ocrdump OCR_DUMP

Also you can use :

$ ocrcheck 
to check for the stats of OCR 

Backing Up and Recovering Voting Disks

What is a voting disk & why its needed ?
The voting disk records node membership information. A node must be
able to access more than half of the voting disks at any time.

For example, if you have seven voting disks configured, then a node must
be able to access at least four of the voting disks at any time. If a
node cannot access the minimum required number of voting disks it is evicted, or removed, from the cluster.

Backing Up Voting Disks

When to backup voting disk ?

1.       After installation
2.       After adding nodes to or deleting nodes from the cluster
3.       After performing voting disk add or delete operations

To make a backup copy of the voting disk, use the Linux dd command. Perform this operation on every voting disk as needed where voting_disk_name is the name of the active voting disk and backup_file_name is the name of the file to which you want to back up the voting disk contents:
dd if=voting_disk_name of=backup_file_name

If your voting disk is stored on a raw device, use the device name in place of voting_disk_name. For example:
dd if=/dev/sdd1 of=/tmp/voting.dmp

Note : When you use the dd command for making backups of the voting disk, the backup can be performed while the Cluster Ready Services (CRS) process is active; you do not need to stop the crsd.bin process before taking a backup of the voting disk.

Recovering Voting Disks

If a voting disk is damaged, and no longer usable by Oracle Clusterware, you can recover the voting disk if you have a backup file.

dd if=backup_file_name of=voting_disk_name