The Oracle installation process for Oracle Clusterware gives you the option of automatically mirroring OCR. You can manually put the mirrored OCRs on a shared Network File System (NFS), or on any cluster file system that is certified by Oracle. Alternatively, you can place OCR on Oracle ASM and allow it to create mirrors automatically, depending on the redundancy option you select.
This section includes the following topics:
You can manually mirror OCR, as described in the "Adding an Oracle Cluster Registry Location" section, if you:
Upgraded to Oracle Clusterware 12c but did not choose to mirror OCR during the upgrade
Created only one OCR location during the Oracle Clusterware installation
Oracle recommends that you configure:
At least three OCR locations, if OCR is configured on non-mirrored or non-redundant storage. Oracle strongly recommends that you mirror OCR if the underlying storage is not RAID. Mirroring can help prevent OCR from becoming a single point of failure.
At least two OCR locations if OCR is configured on an Oracle ASM disk group. You should configure OCR in two independent disk groups. Typically this is the work area and the recovery area.
At least two OCR locations if OCR is configured on mirrored hardware or third-party mirrored volumes.
If the original OCR location does not exist, then you must create an empty (0 byte) OCR location with appropriate permissions before you run the
ocrconfig -add or
ocrconfig -replace commands.
Ensure that the OCR devices that you specify in the OCR configuration exist and that these OCR devices are valid.
Ensure that the Oracle ASM disk group that you specify exists and is mounted.
The new OCR file, device, or disk group must be accessible from all of the active nodes in the cluster.
Oracle Grid Infrastructure Installation Guide for information about creating OCRs
Oracle Automatic Storage Management Administrator's Guide for more information about Oracle ASM disk group management
In addition to mirroring OCR locations, you can also:
Replace an OCR location if there is a misconfiguration or other type of OCR error, as described in the "Replacing an Oracle Cluster Registry Location" section.
Repair an OCR location if Oracle Database displays an OCR failure alert in Oracle Enterprise Manager or in the Oracle Clusterware alert log file, as described in the "Repairing an Oracle Cluster Registry Configuration on a Local Node" section.
Remove an OCR location if, for example, your system experiences a performance degradation due to OCR processing or if you transfer your OCR to RAID storage devices and choose to no longer use multiple OCR locations, as described in the "Removing an Oracle Cluster Registry Location" section.
The operations in this section affect OCR clusterwide: they change the OCR configuration information in the
ocr.loc file on Linux and UNIX systems and the Registry keys on Windows systems. However, the
ocrconfig command cannot modify OCR configuration information for nodes that are shut down or for nodes on which Oracle Clusterware is not running.