How to add disk with Rebalance Power 0 option in ASM disk group
Re balance Power 0
When adding disks to or removing disks from a disk group ,You can effectively disable rebalancing by specifying REBALANCE POWER 0 in the alter diskgroup statement .
When adding disks to disk group in conjuction with REBALNCES POWER 0,the disk become immediately available to the disk group ;however existing data is not moved to the new disks .New data may be written to the new disks .This disk is useful in situations where you need to add disks quickly to a running system and you want to defer the rebalance operation until a later time such a scheduled maintenance periods.
Note - If There is less space in disk group in that case we need to add disk with Re balance Power 0 option So New added disk it will be available in disk group to write new extend(data) . Once off Business hour it will start then you can start the re-balance operation so exiting extend it will move new added disk . That is advantages of adding the disk with Re balance Power 0 option .
1) To find out ASM disk to which need to add in exiting disk group
set linesize 200
col DISK_GROUP_NAME format a20;
col DISK_FILE_PATH format a25;
SELECT
NVL(a.name, '[CANDIDATE]') disk_group_name
, b.path disk_file_path
, b.name disk_file_name
, b.failgroup disk_file_fail_group
,b.header_status
FROM
v$asm_diskgroup a RIGHT OUTER JOIN v$asm_disk b USING (group_number)
ORDER BY a.name;
DISK_GROUP_NAME DISK_FILE_PATH DISK_FILE_NAME DISK_FILE_FAIL_GROUP HEADER_STATU
-------------------- ------------------------- ------------------------------ ------------------------------ ------------
DATA ORCL:DATA1 DATA1 DATA1 MEMBER
DATA ORCL:DATA3 DATA3 DATA3 MEMBER
DATA ORCL:DATA2 DATA2 DATA2 MEMBER
OCRVOTE ORCL:OCR_VOTE3 OCR_VOTE3 OCR_VOTE3 MEMBER
OCRVOTE ORCL:OCR_VOTE1 OCR_VOTE1 OCR_VOTE1 MEMBER
OCRVOTE ORCL:OCR_VOTE2 OCR_VOTE2 OCR_VOTE2 MEMBER
[CANDIDATE] ORCL:OCR_VOTE4 PROVISIONED
[CANDIDATE] ORCL:OCR_VOTE5 PROVISIONED
[CANDIDATE] ORCL:FRA3 PROVISIONED
[CANDIDATE] ORCL:FRA2 PROVISIONED
[CANDIDATE] ORCL:FRA1 FORMER
2) To check the diskgroup size
select name, STATE,TOTAL_MB/1024 "Total GB",USABLE_FILE_MB/1024 "Free GB",(USABLE_FILE_MB/TOTAL_MB)*100 "% Free",TYPE from v$asm_diskgroup;
NAME STATE Total GB Free GB % Free TYPE
-------- ----------- ---------- ---------- ---------- ------
OCRVOTE MOUNTED 13.9951172 6.39453125 45.691159 NORMAL
DATA MOUNTED 83.8330078 39.2246094 46.7889801 NORMAL
3) Add disk with Rebalance Power 0 option in ASM disk group
Login to ASM instance
# sqlplus "/ sys as sysasm"
Then perform the below command .
alter diskgroup DATA ADD DISK 'ORCL:FRA1' rebalance power 0;
Once Off business hour it will start then start the re-balancing operation
alter diskgroup data rebalance power 4;
Monitoring the re-balancing operation from ASMCMD prompt
[oracle@india2 ~]$ asmcmd
ASMCMD> lsop
Group_Name Dsk_Num State Power
DATA REBAL RUN 4
5) Validate the disk is added in disk group or not .
set linesize 200
col DISK_GROUP_NAME format a20;
col DISK_FILE_PATH format a25;
SELECT
NVL(a.name, '[CANDIDATE]') disk_group_name
, b.path disk_file_path
, b.name disk_file_name
, b.failgroup disk_file_fail_group
,b.header_status
FROM
v$asm_diskgroup a RIGHT OUTER JOIN v$asm_disk b USING (group_number)
ORDER BY a.name;
=========================================================
Monitoring ASM alert log file
===============================================================
SQL> alter diskgroup data rebalance power 4;
Diskgroup altered.
---------------------------------------------------------------
Again logfile check its giving below output ..
----------------------------------------------------------------
Sat Mar 25 09:05:18 2017
SQL> alter diskgroup data rebalance power 4
NOTE: GroupBlock outside rolling migration privileged region
NOTE: requesting all-instance membership refresh for group=1
Sat Mar 25 09:05:21 2017
GMON updating for reconfiguration, group 1 at 24 for pid 28, osid 19375
NOTE: group 1 PST updated.
Sat Mar 25 09:05:21 2017
NOTE: membership refresh pending for group 1/0x34570003 (DATA)
GMON querying group 1 at 25 for pid 18, osid 8853
SUCCESS: refreshed membership for 1/0x34570003 (DATA)
SUCCESS: alter diskgroup data rebalance power 4
NOTE: Attempting voting file refresh on diskgroup DATA
NOTE: Refresh completed on diskgroup DATA. No voting file found.
NOTE: starting rebalance of group 1/0x34570003 (DATA) at power 4
Starting background process ARB0
Sat Mar 25 09:05:26 2017
ARB0 started with pid=35, OS id=27292
NOTE: assigning ARB0 to group 1/0x34570003 (DATA) with 4 parallel I/Os
cellip.ora not found.
Sat Mar 25 09:10:00 2017
NOTE: GroupBlock outside rolling migration privileged region
NOTE: requesting all-instance membership refresh for group=1
Sat Mar 25 09:10:03 2017
NOTE: membership refresh pending for group 1/0x34570003 (DATA)
Sat Mar 25 09:10:06 2017
GMON querying group 1 at 26 for pid 18, osid 8853
SUCCESS: refreshed membership for 1/0x34570003 (DATA)
NOTE: Attempting voting file refresh on diskgroup DATA
NOTE: Refresh completed on diskgroup DATA. No voting file found.
Sat Mar 25 09:10:36 2017
NOTE: stopping process ARB0
SUCCESS: rebalance completed for group 1/0x34570003 (DATA)
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