How to Add/Remove OCR file in Oracle 11g RAC ?

How to Add/Remove OCR file in Oracle 11g RAC:

Removing OCR File

(1) Get the Existing OCR file information by running ocrcheck utility.

[root@node1-pub ~]# ocrcheck
Status of Oracle Cluster Registry is as follows :
Version : 2
Total space (kbytes) : 262120
Used space (kbytes) : 3852
Available space (kbytes) : 258268
ID : 744414276
Device/File Name : /u02/ocfs2/ocr/OCRfile_0 <-- OCR
Device/File integrity check succeeded
Device/File Name : /u02/ocfs2/ocr/OCRfile_1 <-- OCR Mirror
Device/File integrity check succeeded

Cluster registry integrity check succeeded

(2) The First command removes the OCR mirror (/u02/ocfs2/ocr/OCRfile_1). If you want to remove the OCR
file (/u02/ocfs2/ocr/OCRfile_1) run the next command.

ocrconfig -replace ocrmirror
ocrconfig -replace ocr

[root@node1-pub ~]# ocrconfig -replace ocrmirror
[root@node1-pub ~]# ocrcheck
Status of Oracle Cluster Registry is as follows :
Version : 2
Total space (kbytes) : 262120
Used space (kbytes) : 3852
Available space (kbytes) : 258268
ID : 744414276
Device/File Name : /u02/ocfs2/ocr/OCRfile_0 <<-- OCR File
Device/File integrity check succeeded

Device/File not configured <-- OCR Mirror not existed any more

Cluster registry integrity check succeeded

Adding OCR

You need to add OCR or OCR Mirror file in a case where you want to move the existing OCR file location to the different Devices.
The below command add ths OCR mirror file if OCR file alread exists.

(1) Get the Current status of OCR:

[root@node1-pub ~]# ocrconfig -replace ocrmirror
[root@node1-pub ~]# ocrcheck
Status of Oracle Cluster Registry is as follows :
Version : 2
Total space (kbytes) : 262120
Used space (kbytes) : 3852
Available space (kbytes) : 258268
ID : 744414276
Device/File Name : /u02/ocfs2/ocr/OCRfile_0 <<-- OCR File
Device/File integrity check succeeded

Device/File not configured <-- OCR Mirror does not exist

Cluster registry integrity check succeeded

As You can see, I only have one OCR file but not the second file which is OCR Mirror.
So, I can add second OCR (OCR Mirror) as below command.

ocrconfig -replace ocrmirror

[root@node1-pub ~]# ocrconfig -replace ocrmirror /u02/ocfs2/ocr/OCRfile_1
[root@node1-pub ~]# ocrcheck
Status of Oracle Cluster Registry is as follows :
Version : 2
Total space (kbytes) : 262120
Used space (kbytes) : 3852
Available space (kbytes) : 258268
ID : 744414276
Device/File Name : /u02/ocfs2/ocr/OCRfile_0
Device/File integrity check succeeded
Device/File Name : /u02/ocfs2/ocr/OCRfile_1
Device/File integrity check succeeded

Cluster registry integrity check succeeded

You can have at most 2 OCR devices (OCR itself and its single Mirror) in a cluster. Adding extra Mirror gives you below error message

[root@node1-pub ~]# ocrconfig -replace ocrmirror /u02/ocfs2/ocr/OCRfile_2
PROT-21: Invalid parameter
[root@node1-pub ~]#