How to Restore ASM Based OCR After Complete Loss of the CRS Diskgroup on Linux/Unix Systems (Doc ID 1062983.1)

It is not possible to directly restore a manual or automatic OCR backup if the OCR is located in an ASM disk group. 

This is caused by the fact that the command 'ocrconfig -restore' requires ASM to be up & running in order to restore an OCR backup to an ASM disk group. However, for ASM to be available, the CRS stack must have been successfully started. 

For the restore to succeed, the OCR also must not be in use (r/w), i.e. no CRS daemon must be running while the OCR is being restored.

A description of the general procedure to restore the OCR can be found in the  documentation, this document explains how to recover from a complete loss of the ASM disk group that held the OCR and Voting files in a 11gR2 Grid environment.

Note:- From 12.2 onwards, OCR backups are located in ASM diskgroup. Refer Doc ID 2569847.1 having specific restoration steps involved when the OCR backup is located in ASM disk group.

When using an ASM disk group for CRS there are typically 3 different types of files located in the disk group that potentially need to be restored/recreated:

1) the Oracle Cluster Registry file (OCR)

2) the Voting file(s)

3) the shared SPFILE for the ASM instances

The following example assumes that the OCR was located in a single disk group used exclusively for CRS. The disk group has just one disk using external redundancy.

Since the CRS disk group has been lost the CRS stack will not be available on any node.

The following settings used in the example would need to be replaced according to the actual configuration:

GRID user:                       oragrid

GRID home:                       /u01/app/11.2.0/grid ($CRS_HOME)

ASM disk group name for OCR:     CRS

ASM/ASMLIB disk name:            ASMD40

Linux device name for ASM disk:  /dev/sdh1

Cluster name:                    rac_cluster1

Nodes:                           racnode1, racnode2

1. Locate the latest automatic OCR backup

When using a non-shared CRS home, automatic OCR backups can be located on any node of the cluster

[root@rac01.samik.com ~]# ocrconfig -showbackup

rac01.samik.com     2024/12/02 07:22:31     +OCRVD:/POCDB-SCAN-Cluster/OCRBACKUP/backup00.ocr.271.1186644149     2204791795
rac01.samik.com     2024/12/02 03:22:29     +OCRVD:/POCDB-SCAN-Cluster/OCRBACKUP/backup01.ocr.270.1186629747     2204791795
rac01.samik.com     2024/12/01 23:22:26     +OCRVD:/POCDB-SCAN-Cluster/OCRBACKUP/backup02.ocr.269.1186615345     2204791795
rac01.samik.com     2024/11/30 15:21:17     +OCRVD:/POCDB-SCAN-Cluster/OCRBACKUP/day.ocr.266.1186413679     2204791795
rac01.samik.com     2024/11/22 19:17:22     +OCRVD:/POCDB-SCAN-Cluster/OCRBACKUP/week.ocr.268.1185736643     220479179

2. Make sure the Grid Infrastructure is shutdown on all nodes

Given that the OCR diskgroup is missing, the GI stack will not be functional on any node, however there may still be various daemon processes running.  On each node shutdown the GI stack using the force (-f) option:

# $CRS_HOME/bin/crsctl stop crs -f

3. Start the CRS stack in exclusive mode

On the node that has the most recent OCR backup, log on as root and start CRS in exclusive mode, this mode will allow ASM to start & stay up without the presence of a Voting disk and without the CRS daemon process (crsd.bin) running.

11.2.0.2 and above:

# $CRS_HOME/bin/crsctl start crs -excl -nocrs
CRS-4123: Oracle High Availability Services has been started.

4. Label the CRS disk for ASMLIB use

If using ASMLIB the disk to be used for the CRS disk group needs to stamped first, as user root do:

# /usr/sbin/oracleasm createdisk ASMD40 /dev/sdh1
Writing disk header: done
Instantiating disk: done

5. Create the CRS diskgroup via sqlplus

The disk group can now be (re-)created via sqlplus from the grid user. The compatible.asm attribute must be set to 11.2 in order for the disk group to be used by CRS:

$ sqlplus / as sysasm
SQL*Plus: Release 11.2.0.1.0 Production on Tue Mar 30 11:47:24 2010
Copyright (c) 1982, 2009, Oracle. All rights reserved.
Connected to:
Oracle Database 11g Enterprise Edition Release 11.2.0.1.0 - Production
With the Real Application Clusters and Automatic Storage Management options

SQL> create diskgroup CRS external redundancy disk 'ORCL:ASMD40' attribute 'COMPATIBLE.ASM' = '11.2';

Diskgroup created.

6. Restore the latest OCR backup

Now that the CRS disk group is created and mounted the OCR can be restored - must be done as the root user:

Note:- Our backup is on ASM Disk group

# $CRS_HOME/bin/ocrconfig -restore backup00.ocr

7. Start the CRS daemon on the current node (11.2.0.1 only !)

Now that the OCR has been restored the CRS daemon can be started, this is needed to recreate the Voting file. Skip this step for 11.2.0.2.0.

# $CRS_HOME/bin/crsctl start res ora.crsd -init
CRS-2672: Attempting to start 'ora.crsd' on 'racnode1'
CRS-2676: Start of 'ora.crsd' on 'racnode1' succeeded

8. Recreate the Voting file

The Voting file needs to be initialized in the CRS disk group:

# $CRS_HOME/bin/crsctl replace votedisk +CRS
Successful addition of voting disk 00caa5b9c0f54f3abf5bd2a2609f09a9.
Successfully replaced voting disk group with +CRS.
CRS-4266: Voting file(s) successfully replaced

9. Recreate the SPFILE for ASM (optional)

Please note:

Starting with 11gR2 ASM can start without a PFILE or SPFILE, so if you are

- not using an  SPFILE for ASM

- not using a shared SPFILE for ASM

- using a shared SPFILE not stored in ASM (e.g. on cluster file system)

this step possibly should be skipped.

Also use extra care in regards to the asm_diskstring parameter as it impacts the discovery of the voting disks.

Please verify the previous settings using the ASM alert log.

Prepare a pfile (e.g. /tmp/asm_pfile.ora) with the ASM startup parameters - these may vary from the example below. If in doubt consult the ASM alert log  as the ASM instance startup should list all non-default parameter values. Please note the last startup of ASM (in step 2 via CRS start) will not have used an SPFILE, so a startup prior to the loss of the CRS disk group would need to be located.

*.asm_power_limit=1
*.diagnostic_dest='/u01/app/oragrid'
*.instance_type='asm'
*.large_pool_size=12M
*.remote_login_passwordfile='EXCLUSIVE'
Now the SPFILE can be created using this PFILE:

$ sqlplus / as sysasm
SQL*Plus: Release 11.2.0.1.0 Production on Tue Mar 30 11:52:39 2010
Copyright (c) 1982, 2009, Oracle. All rights reserved.

Connected to:
Oracle Database 11g Enterprise Edition Release 11.2.0.1.0 - Production
With the Real Application Clusters and Automatic Storage Management options

SQL> create spfile='+CRS' from pfile='/tmp/asm_pfile.ora';

File created.

10. Shutdown CRS

Since CRS is running in exclusive mode, it needs to be shutdown  to allow CRS to run on all nodes again. Use of the force (-f) option may be required:

# $CRS_HOME/bin/crsctl stop crs -f
...
CRS-2793: Shutdown of Oracle High Availability Services-managed resources on 'auw2k3' has completed
CRS-4133: Oracle High Availability Services has been stopped.

11. Rescan ASM disks

If using ASMLIB rescan all ASM disks on each node as the root user:

# oracleasm scandisks
Reloading disk partitions: done
Cleaning any stale ASM disks...
Scanning system for ASM disks...
Instantiating disk "ASMD40"

12. Start CRS

As the root user submit the CRS startup on all cluster nodes:

# $CRS_HOME/bin/crsctl start crs
CRS-4123: Oracle High Availability Services has been started.

13. Verify CRS

To verify that CRS is fully functional again:

# $CRS_HOME/bin/crsctl check cluster -all
**************************************************************
racnode1:
CRS-4537: Cluster Ready Services is online
CRS-4529: Cluster Synchronization Services is online
CRS-4533: Event Manager is online
**************************************************************
racnode2:
CRS-4537: Cluster Ready Services is online
CRS-4529: Cluster Synchronization Services is online
CRS-4533: Event Manager is online
**************************************************************

# $CRS_HOME/bin/crsctl status resource -t