Use this clause to manually rebalance the disk group. Automatic Storage Management redistributes datafiles evenly across all drives. This clause is rarely necessary, because Automatic Storage Management allocates files evenly and automatically rebalances diskgroups when the storage configuration changes. However, it is useful if you want to use the POWER clause to control the speed of what would otherwise be an automatic rebalance operation.

POWER In the POWER clause, specify a value from 0 to 11, where 0 stops the rebalance operation and 11 permits Automatic Storage Management to execute the rebalance as fast as possible. The value you specify in the POWER clause defaults to the value of the ASM_POWER_LIMIT initialization parameter.

If you omit the POWER clause, then Automatic Storage Management executes both automatic and specified rebalance operations at the power determined by the value of the ASM_POWER_LIMIT initialization parameter.

WAIT | NOWAIT Use this clause to specify when in the course of the rebalance operation control should be returned to the user.

Specify WAIT to allow a script. that adds or removes disks to wait for the disk group to be rebalanced before returning control to the user. You can explicitly terminate a rebalance operation running in WAIT mode, although doing so does not undo any completed disk add or drop operation in the same statement.

Specify NOWAIT if you want control returned to the user immediately after the statement is issued. This is the default.

You can monitor the progress of the rebalance operation by querying the V$ASM_OPERATION dynamic performance view.

注意：rebalance power 5 中后面跟的数字范围是1到11.rebalance power 意思是指加入磁盘后，自动重组的比值，数字越大，重组速度越快，但是会影响在线数据库运行。默认是1.