What is OCR and voting disk?

The voting disk is a file that manages information about node membership, and the OCR is a file that manages the cluster and Real Application Clusters (RAC) database configuration information. The Oracle Clusterware installation process creates the voting disk and the OCR on a shared storage volume.

Why are there 3 voting discs?

For high availability, Oracle recommends that you have a minimum of three voting disks. – If a node cannot access the minimum required number of voting disks it is evicted, or removed, from the cluster. – All nodes in the RAC cluster register their heart-beat information on the voting disks.

What is the role of the voting disk?

Voting disk is a file that manages information about node membership.It is located on the shared cluster system or a shared raw device file or Oracle ASM(11gr2 onwards) . Its primary purpose is to help in a situation where the private network communication fails.

Where is OCR and voting disk?

OCR config file “/etc/oracle/ocr. loc” check successful Disk group for ocr location “+DATA” is available on all the nodes Checking OCR backup location “/u01/app/12.1. 0.2/grid/cdata/racscan” OCR backup location “/u01/app/12.1.

What is the maximum count of OCR files in cluster?

five OCR locations
You can have up to five OCR locations. However, each successive run must point to a different disk group.

What voting disk contains?

What Information is stored in VOTING DISK/FILE? It contains 2 types of data. Static data: Information about the nodes in cluster. Dynamic data: Disk heartbeat logging. It contains the important details of the cluster nodes membership like.

Why do we need odd number of voting discs?

1) Why do we have to create odd number of voting disk? As far as voting disks are concerned, a node must be able to access strictly more than half of the voting disks at any time. So if you want to be able to tolerate a failure of n voting disks, you must have at least 2n+1 configured. (n=1 means 3 voting disks).

What do you mean by OCR?

Optical Character Recognition
OCR stands for “Optical Character Recognition.” It is a technology that recognizes text within a digital image. It is commonly used to recognize text in scanned documents and images. OCR software can be used to convert a physical paper document, or an image into an accessible electronic version with text.

What is automatic backup policy for OCR voting disk?

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.

How do I backup my voting disk?

How to Backup Clusterware OCR and Voting Disk

1. OCR Dumps. Oracle provides an utility ocrconfig to export OCR data to a dump file like this:
2. OCR Backups. Since 11g (11.1), the clusterware backs up OCR automatically every 4 hours by Cluster Ready Services Daemon (CRSD).
3. Use dd Command.
4. Rely on OCR Backups.

Why do we need an odd number of voting discs?

Why we need to keep odd number of voting disks ? Oracle expects that you will configure at least 3 voting disks for redundancy purposes. You should always configure an odd number of voting disks >= 3. This is because loss of more than half your voting disks will cause the entire cluster to fail.

Where does the OCR go in a cluster?

When a node is added or removed from the cluster it is in the OCR that this information gets recorded. It is the center of cluster information and must be in storage shared by all nodes, can have up to 4 mirrors, can be managed through the “ocrconfig”, “ocrdump” and “ocrcheck” utilities, it is preferable to use these as Root.

What is OCR and what is CRS resource?

OCR contains information like which database instances run on which nodes and which services runs on which database. CRS Resource – anything that Oracle Clusterware manages is classified as CRS resource like database, instance, service, listener, VIP address and so on.

How to add OCR to an oracle ASM disk group?

To add OCR to an Oracle ASM disk group, ensure that the Oracle Clusterware stack is running and run the following command as root: # ocrconfig -add +new_disk_group You can run this command more than once if you add multiple OCR locations. You can have up to five OCR locations.

How to manage OCR and the Oracle local registry?

To manage OCR and the Oracle Local Registry (OLR), use OCRCONFIG, OCRDUMP, and OCRCHECK . OCR contains information about all Oracle resources in the cluster. OLR is a registry similar to OCR located on each node in a cluster, but contains information specific to each node.