For COMPATIBLE.ASM disk group attribute is set to 220.127.116.11 or higher, the range of values is 0 to 1024.
For COMPATIBLE.ASM disk group attribute is set to lower than 18.104.22.168 , the range of values is 0 to 11.
We can change the rebalance power either at the ASM instance level or at the individual disk group level.
Changing the value at the instance level, this will alter the power limit for any new operations, but not the existing ones.
SQL > alter system set asm_power_limit=5 scope=both;
Change the value at the disk group level, this will change an existing operation on the diskgroup involved in the current operation.
SQL> alter diskgroup diskgroup1 rebalance power 8;
The effect of the change can be viewed from v$asm_operation:
SQL> select * from gv$asm_operation;