Oracle cluster registry is a crucial file which stores the cluster configuration information and all the node database instance details.
We can choose separate diskgroups for OCR as candidate disk to store it on ASM diskgroup during installation
Without OCR file ,the clusterware couldnot identify the instance information of the neighbouring nodes!!
CRS daemon stores the configuration of OCR and takes the automatic backup of OCR for every 4 hours on the RAC
OCR architecture:
In 11gr2 and 12c versions,OCR can have upto five mirrored copies
The storage where datafiles reside should be accessed by all the nodes.
The CRS daemon is responsible for writing the data and disk I/O from the cache in the memory
To get the details of the previous backups we can use the ocrconfig!!
[oracle@RAC1 ~]$ ocrconfig -showbackup
rac2 2019/12/16 15:49:43 /grid/11.2.0/grid/cdata/RAC-scan/backup00.ocr
rac2 2019/12/16 11:47:27 /grid/11.2.0/grid/cdata/RAC-scan/backup01.ocr
rac3 2019/11/08 02:15:53 /grid/11.2.0/grid/cdata/RAC-scan/backup02.ocr
rac2 2019/12/16 11:47:27 /grid/11.2.0/grid/cdata/RAC-scan/day.ocr
rac2 2019/12/16 11:47:27 /grid/11.2.0/grid/cdata/RAC-scan/week.ocr
rac2 2019/07/16 16:03:14 /grid/backup_20190716_160314.ocr
rac2 2019/07/16 13:41:40 /grid/11.2.0/grid/cdata/RAC-scan/backup_20190716_134140.ocr
rac2 2019/07/16 13:12:30 /grid/11.2.0/grid/cdata/RAC-scan/backup_20190716_131230.ocr
rac2 2019/07/16 13:07:47 /grid/11.2.0/grid/cdata/RAC-scan/backup_20190716_130747.ocr
To change the backup of OCR to a dedicated directory
[oracle@RAC1 ~]$ ocrconfig -backuploc /home/oracle
To list the OCR and its mirror disks and to verify the integrity of each file
[oracle@RAC1 ~]$ ocrcheck
Status of Oracle Cluster Registry is as follows :
Version : 3
Total space (kbytes) : 262120
Used space (kbytes) : 3732
Available space (kbytes) : 258388
ID : 2047356075
Device/File Name : +EXT
Device/File integrity check succeeded
Device/File not configured
Device/File not configured
Device/File not configured
Device/File not configured
Cluster registry integrity check succeeded
Logical corruption check bypassed due to non-privileged user
To verify the integrity from all the nodes!
[oracle@RAC1 ~]$ cluvfy comp ocr -n all -verbose
Verifying OCR integrity
Checking OCR integrity...
Checking the absence of a non-clustered configuration...
All nodes free of non-clustered, local-only configurations
ASM Running check passed. ASM is running on all specified nodes
Checking OCR config file "/etc/oracle/ocr.loc"...
OCR config file "/etc/oracle/ocr.loc" check successful
Disk group for ocr location "+EXT" available on all the nodes
NOTE:
This check does not verify the integrity of the OCR contents. Execute 'ocrcheck' as a privileged user to verify the contents of OCR.
OCR integrity check passed
Verification of OCR integrity was successful.
To take manual backup of OCR
[oracle@RAC1 ~]$ ocrdump <filename>
Sometimes there can be situations to take manual backups of OCR though it is automatic!!
