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Oracle Cluster Registry (OCR)
The Oracle Cluster Registry is a binary file which can be mirrored for redundancy. It holds the entire
cluster related information, such as instances names, resources, etc.
The location of the OCR is /var/opt/oracle/ocr.loc:
oracle@ita018[RAC1]:/home/oracle$ cat /var/opt/oracle/ocr.loc
ocrconfig_loc=/hpap/rdsk/hpap0
local_only=FALSE
Oracle provides an automatic mechanism which performs regular backups of the OCR. The OCR
daemons are in charge of these periodic snapshots. It has to be mentioned that these backups are
only taken on the OCRMASTER host (as long as it is available).
It can be verified with the following utility:
oracle@ita018[RAC1]:/home/oracle$ ocrconfig -showbackup
ita018 2007/09/10 10:43:57 /opt/oracle/product/CRS/cdata/crs
ita018 2007/09/10 06:43:57 /opt/oracle/product/CRS/cdata/crs
ita018 2007/09/10 02:43:56 /opt/oracle/product/CRS/cdata/crs
ita018 2007/09/09 02:43:54 /opt/oracle/product/CRS/cdata/crs
ita018 2007/09/04 14:43:11 /opt/oracle/product/CRS/cdata/crs
If we look in the default location of the OCR backups, $ORA_CRS_HOME/cdata/”cluster_name”, we
see the different backups which are kept:
oracle@ita018[RAC1]:/opt/oracle/product/CRS/cdata/crs$ date
Mon Sep 10 14:14:12 METDST 2007
oracle@ita018[RAC1]:/opt/oracle/product/CRS/cdata/crs$ ll -rta
total 109026
drwxrwxr-x 4 oracle oinstall 96 Jul 20 17:02 ..
-rw-r--r-- 1 root root 8654848 Sep 4 14:43 week.ocr
-rw-r--r-- 1 root root 9433088 Sep 9 02:43 day.ocr
-rw-r--r-- 1 root root 9433088 Sep 10 02:43 day_.ocr
-rw-r--r-- 1 root root 9433088 Sep 10 02:43 backup02.ocr
-rw-r--r-- 1 root root 9433088 Sep 10 06:43 backup01.ocr
drwxrwxr-x 2 oracle oinstall 1024 Sep 10 10:43 .
-rw-r--r-- 1 root root 9433088 Sep 10 10:43 backup00.ocr
These files will be backed when we perform a file system backup of the ORA_CRS_HOME directory.
Oracle Voting Disk
The Oracle Voting Disk is used mainly as a Disk Heartbeat by the Node Monitor to detect “split
brain” situations and decide on the node eviction.
There is no automatic mechanism provided by Oracle for backing up the Oracle Voting Disk. As we
need to guarantee the recoverability of the Voting Disk in case of loss, at least one backup needs to
be performed after the cluster installation and every time the Voting configuration is changed
(add/remove of nodes).
The location of the Voting Disk can be queried with this command:
oracle@ita018[RAC1]:/home/oracle$ crsctl query css votedisk
0. 0 /hpap/rdsk/hpap1
located 1 votedisk(s).
