Voting Disk files are files that Oracle Clusterware uses to verify cluster node
Voting Disk File contains 2 types of data
• Static data: Information about the nodes in cluster
• Dynamic data: Disk heartbeat logging
Why should we have ODD number of Voting Disk?
A node must be able to access more than half of the voting disks at any time.
Let us consider 2 node clusters with even number of voting disks say 2.
- Let node 1 is able to access voting disk 1.
- Node 2 is able to access voting disk 2.
- From the above steps, we see that we don’t have any common file where clusterware can check the heartbeat of both the nodes.
- If we have 3 voting disks and both the nodes are able to access more than half ie., 2 voting disks, there will be atleast one disk which will be accessed by both the nodes. The clusterware can use this disk to check the heartbeat of the nodes.
- A node not able to do so will be evicted from the cluster by another node that has more than half the voting disks to maintain the integrity of the cluster.
Oracle recommends that you configure multiple voting disks during Oracle Clusterware installation to improve availability. If you choose to put the voting disks into an Oracle ASM disk group, then Oracle ASM ensures the configuration of multiple voting disks if you use a normal or high redundancy disk group.
External redundancy = 1 Voting disk
Normal redundancy = 3 Voting disks
High redundancy = 5 Voting disks
You can have up to 32 voting disks in your cluster
Although the Voting disk contents are not changed frequently, you will need to back up the Voting disk file every time
• You add or remove a node from the cluster or
• Immediately after you configure or upgrade a cluster.
Identify the voting disk location :
$ crsctl query css votedisk -- ----- ----------------- --------- --------- ## STATE File Universal Id File Name Disk group 1. ONLINE 6f57843d89464c46ea747362e8a3fa43 (/dev/sdb1) [DATA] 2. ONLINE 7c54856e98474f61bf349401e7c9fb95 (/dev/sdc1) [DATA] 3. ONLINE 9c46232b76234f61fc934673d5c8ec59 (/dev/sdd1) [DATA]
Backup the voting disk:
Voting Disks In 11g release 2 you no longer have to take voting disks backup. In fact according to Oracle documentation restoration of voting disks that were copied using the "dd" or "cp" command may prevent your clusterware from starting up. So, In 11g Release 2 your voting disk data is automatically backed up in the OCR whenever there is a configuration change. Also the data is automatically restored to any voting that is added. OCR BACKUP Automatic backups : - a) Oracle Clusterware (CRSD) automatically creates OCR backups every 4 hours. b) A backup is created for each full day. c) A backup is created at the end of each week. d) Oracle Database retains the last three copies of OCR. Manual backups: - a) can be taken using the "ocrconfig -manualbackup" command Example: $ocrconfig -manualbackup
Run the following command to list the backup files:
Run the following command to inspect the contents and verify the integrity of the backup file:
ocrdump -backupfile backup_file_name
Run the following command to change the location where OCR creates backups:
# ocrconfig -backuploc file_name For example, to specify an OCR backup location in a directory: # ocrconfig -backuploc Grid_home/cdata/cluster3