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
