Oracle Cluster Registry (OCR) The OCR contains cluster and database configuration information for RAC and Cluster Ready Services (CRS) such as the cluster node list, and cluster database instances to node mapping, and CRS application resource profiles. The OCR is a shared file located in a cluster file system.

What is OCR disk in Oracle RAC?

Oracle Clusterware includes two important components: the voting disk and the OCR. The voting disk is a file that manages information about node membership, and the OCR is a file that manages cluster and Oracle RAC database configuration information.

What is OLR and OCR in RAC?

Oracle Cluster Registry (OCR) and Oracle Local Registry (OLR) are two very important components of a Grid Infrastructure that help manage the cluster resources. In a nutshell, OCR is used by CRSd and OLR by the OHASd.

What is the use of OCR in Oracle?

OCR manages Oracle Clusterware and Oracle RAC database configuration information. OLR resides on every node in the cluster and manages Oracle Clusterware configuration information for each particular node. Voting disks manage information about node membership.

How do I check my OCR?

OCR integrity check passed Verification of OCR integrity was successful. Step 1 :- Stop cluster on each node (as Root user).
...
Oracle Cluster Registry in RAC (OCR)

1. cluster database instance to node mapping.
2. cluster node list.
3. CRS application resource profiles.
4. Local listener & scan listener.
5. VIP,Scan IP & Services.

OCR and OLR - RAC 09

What is an OCR code?

Optical character recognition (OCR) technology is a business solution for automating data extraction from printed or written text from a scanned document or image file and then converting the text into a machine-readable form to be used for data processing like editing or searching.

What is OCR on a check?

Some companies will augment the magnetic reading of the item's MICR characters with optical character recognition (OCR) to verify the read. OCR uses the scanner's optical sensor to capture the characters on the MICR line of the check.

What is scan IP and VIP in Oracle RAC?

SCAN virtual IP addresses (VIPs) function like node VIPs. However, unlike node VIPs, SCAN VIPs can run on any node in the cluster. Clients (users or applications) that connect using a SCAN instead of a node VIP name or address do not have to update the list of node names or addresses in their local tnsnames.

What is split brain in RAC?

Split Brain is often used to describe the scenario when two or more nodes in a cluster, lose connectivity with one another but then continue to operate independently of each other, including acquiring logical or physical resources, under the incorrect assumption that the other process(es) are no longer operational or ...

What is CSSD in Oracle RAC?

Oracle Cluster Synchronization Services daemon (CSSD) Cluster Ready Services daemon (CRSD), which is the main engine for maintaining availability of resources.

What is Cache Fusion in RAC?

Oracle RAC Cache Fusion is simply where Oracle RAC transfers data blocks from the buffer cache of one instance to the buffer cache of another instance across the cluster interconnect. Transfers across this private network are in order of magnitude better than disk I/O activity and they help Oracle RAC performance.

What is node eviction in Oracle RAC?

A node eviction is done when a heartbeat indicates that a node is not responding, and the evicted node is re-started so that it can continue to partiipate in the cluster. Reason for RAC node evictions. There are many reasons for a RAC node eviction.

How do you recover from OCR?

Use the following steps to restore the voting disk from the OCR backup.

1. Step 1: Disable the CRS automatic start service. ...
2. Step 2: Restart the node. ...
3. Step 3: Verify that the CSR service did not start. ...
4. Step 4: Clear the header of the voting disk. ...
5. Step 5: Start the cluster. ...
6. Step 6: Start the ASM with a PFILE.

How do I find my OCR backup location?

First check exact location of automatic OCR backup location using "ocrconfig -showbackup" command. Because this automatic backup of OCR is physical copies of Oracle Cluster Registry. There is no need to bring down Cluster to take this physical backup of OCR.

How do I backup my OCR and voting disk?

How to Backup 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.

What is heartbeat in Oracle RAC?

Answer: A heartbeat is a polling mechanism, similar to a ping, that monitors the availability of other servers in a RAC system. The heartbeat is a type of polling mechanism that is sent over the cluster interconnect to ensure that all RAC nodes are available. The heartbeat is part of the clusterware node monitoring.

What is GCS and GES in RAC?

The GCS and GES are integrated components of Real Application Clusters that coordinate simultaneous access to the shared database and to shared resources within the database and database cache. GES and GCS together maintain a Global Resource Directory (GRD) to record information about resources and enqueues.

What is IO fencing in Oracle RAC?

I/O fencing is a feature that prevents data corruption in the event of a communication breakdown in a cluster. To provide high availability, the cluster must be capable of taking corrective action when a node fails. In this situation, SF Oracle RAC configures its components to reflect the altered membership.

Why are there 3 SCAN listeners in Oracle RAC?

It reduces connectivity time for application or web based end users. Normally 3 SCANs are capable enough to handle hundreds of new connections in a span of few seconds. Still if you feel that default 3 SCAN listeners are not enough for your environment then you have an option to add few more scan listeners.

Why does Oracle RAC have 3 SCAN?

"In case, a 2-node-cluster is used (for which 3 IPs are still recommended for simplification reasons), one server in the cluster will host two sets of SCAN resources under normal operations." You don't need 3 SCAN VIPs. You can implement it with 1 or 2 if you choose, but it would be a bad idea.

How many IPs are there in RAC?

So in summary, there are at minimum 2 physical network devices, and 3 IP addresses per RAC node. Oracle 11g RAC introduces the concept of the single client access name, or SCAN. The idea behind this is that applications/client will only connect to a single domain name when connecting to a RAC database.

Why is OCR used?

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 OCR and MICR?

OCR stands for Optical Character Recognition. MICR stands for Magnetic Ink Character Reader. 2. Scanning. OCR can scan any kind of printed text.

Is OCR input or output?

OCR is an input device used to read a printed text. OCR scans the text optically, character by character, converts them into a machine readable code, and stores the text on the system memory.