Change Oracle ASM Diskgroup Redundancy

Summary

This process is utilized to change the redundancy of an existing diskgroup.  The example utilizes a RAC environment, but same process can be utilized for single instance environment with small variation.

Basic High Level Process

1.       Backup all databases that are on disk group(s) where redundancy needs changed.

2.       Remove disk group

3.       Create disk group at new redundancy level

4.       Restore databases

Process Detail Steps

1.  Shutdown database(s) to get all activity out of database

Example

srvctl stop database –d db1

. oraenv

db21

sqlplus / as sysdba

shutdown immediate

2. Start database instances (in RAC on node 1 and make sure all other instances of the database(s) are down) in restricted mode this will make sure no activity gets into database.

. oraenv

db1

sqlplus / as sysdba

startup mount

. oraenv

db21

sqlplus / as sysdba

startup mount

3. Take backup for each database on the diskgroup(s) where redundancy needs to be changed.

Example uses standard script to do level 0 hotbackup and backs up archive logs since database is in mount state no changes going on in DBs:

/u01/app/oracle/scripts/rman_hot_backup_rac.sh db1 0

/u01/app/oracle/scripts/rman_hot_backup_rac.sh db21 0

4. Shut database(s) down and re-start database instance(s) in nomount state, in this state we can do what we need with the disk groups and it be set to restore databases once the disk group(s) work is complete.

Example:

. oraenv

db1

sqlplus / as sysdba

shutdown immediate

startup nomount

exit

. oraenv

db21

sqlplus / as sysdba

shutdown immediate

startup nomount

5. Remove Existing diskgroup(s) that need redundancy changed, in a RAC environment make sure disk groups are dismounted from other ASM instances or other ASM instances are shutdown.

** On other nodes in ASM instance dismount the diskgroups

alter diskgroup data dismount ;

alter diskgroup reco dismount ;

Example

. oraenv

+ASM1

sqlplus / as sysasm

DROP DISKGROUP DATA INCLUDING CONTENTS;

DROP DISKGROUP RECO INCLUDING CONTENTS;

6. Recreate Disk Group(s) so that they are a different redundancy in this example we are doing external redundancy and au_size of 4M

Example:

. oraenv

+ASM1

sqlplus / as sysasm

CREATE DISKGROUP DATA EXTERNAL REDUNDANCY DISK '/dev/sdd1' SIZE 255996M ,

'/dev/sde1' SIZE 255996M ,

'/dev/sdf1' SIZE 255996M ,

'/dev/sdg1' SIZE 255996M 

ATTRIBUTE 'compatible.asm'='11.2.0.0.0','au_size'='4M' ;

CREATE DISKGROUP RECO EXTERNAL REDUNDANCY DISK '/dev/sdh1' SIZE 255996M ,

'/dev/sdi1' SIZE 255996M 

ATTRIBUTE 'compatible.asm'='11.2.0.0.0','au_size'='4M' ;

7. Check that disk groups are the right size now and au_size and state is good.

select name, allocation_unit_size/1024/1024, total_mb, usable_file_mb, type, state

from v$asm_diskgroup ;

8. Restore database(s)

Example:

.oraenv

db1

rman target=/ catalog=/@rman

SET DBID 807730062;

run {

RESTORE CONTROLFILE FROM AUTOBACKUP ;

ALTER DATABASE MOUNT;

}

run {

restore database ;

recover database ;

}

.oraenv

db21

rman target=/ catalog=/@rman

SET DBID 807730062;

run {

RESTORE CONTROLFILE FROM AUTOBACKUP ;

ALTER DATABASE MOUNT;

}

run {

restore database ;

recover database ;

}

9. Open database(s) with resetlogs         

Example:

. oraenv

db1

sqlplus / as sysdba

alter database open resetlogs ;

. oraenv

db21

sqlplus / as sysdba

alter database open resetlogs ;

10. Check control file entries as after restore of control file then names change, then set the

initialization parameter to the new names

Example:

. oraenv

+ASM1

asmcmd

Check control files for the databases in their locations and update the init.ora or spfile

alter system set control_files='+RECO/db/controlfile/current.256.839933795', '+DATA/db/controlfile/current.257.839933795' scope=spfile sid='*' ;

vi init.ora file so just need to update init.ora file

*.control_files='+RECO/db2/controlfile/current.268.839934043', '+DATA/db2/controlfile/current.271.839934043'

11. bounce databases after restore and recover to ensure all is back to normal

Example:

. oraenv

db1

sqlplus / as sysdba

shutdown immediate

exit

srvctl start database -d db

. oraenv

db21

sqlplus / as sysdba

shutdown immediate

startup

exit

12. Take new level 0 hot backups of both databases.

Example:

/u01/app/oracle/scripts/rman_hotbackup_rac.sh db1 0 &

/u01/app/oracle/scripts/rman_hotbackup_rac.sh db21 0

ALL DONE!!