How to Speed up ASM Disks Rebalancing Operation

How to Speed up ASM Disks Rebalancing Operation:

When I tried to drop two ASM disks (each ~ 100GB) from the ASM DISKGROUP I have noticed that the rebalance operation is taking more than an hour by querying the v$asm_operation.

SELECT group_number, operation, state, power, est_minutes FROM v$asm_operation;

Here is the ouput from the above command:

GROUP_NUMBER OPERA STAT POWER EST_MINUTES
------------ ----- ---- ---------- -----------
2 REBAL RUN 1 62

The total size of the diskgroup before dropping the two disks of interest is 500 GB of which 250 GB is free. So I decided to drop two ASM disks of each ~ 100 GB using ASMCA.

After doing little research, I altered the rebalance power for the diskgroup using the following command:

alter diskgroup DISKGROUP rebalance power 5;
The rebalance operation started again, this time the estimated time came down to about 15 minutes.

SELECT group_number, operation, state, power, est_minutes FROM v$asm_operation;

Here is the output from the above

GROUP_NUMBER OPERA STAT POWER EST_MINUTES
------------ ----- ---- ---------- -----------
2 REBAL RUN 5 15

Until the rebalance operation is finished, you shouldn’t touch the underlying physical disks.