You can use the ALTER DISKGROUP SQL statement to alter a disk group configuration. You can add, resize, or drop disks while the database remains online. Whenever possible, multiple operations in a single ALTER DISKGROUP statement are recommended. Grouping operations in a single ALTER DISKGROUP statement can reduce rebalancing operations.
Oracle ASM automatically rebalances when the configuration of a disk group changes. By default, the ALTER DISKGROUP statement does not wait until the operation is complete before returning. Query the V$ASM_OPERATION view to monitor the status of this operation.
Use the REBALANCE WAIT clause to cause the ALTER DISKGROUP statement processing to wait until the rebalance operation is complete before returning. This is especially useful in scripts. The statement also accepts a REBALANCE NOWAIT clause that invokes the default behavior of conducting the rebalance operation asynchronously in the background.
You can interrupt a rebalance running in wait mode by typing CTRL+C on most platforms. This causes the statement to return immediately with the message ORA-01013: user requested cancel of current operation, and then to continue the operation asynchronously. Typing CTRL+C does not cancel the rebalance operation or any disk add, drop, or resize operations.
To control the speed and resource consumption of the rebalance operation, you can include the REBALANCE POWER clause in statements that add, drop, or resize disks. Refer to "Manually Rebalancing Disk Groups" for more information about this clause.
This section contains the following topics:
The ALTER DISKGROUP SQL statement in the Oracle Database SQL Language Reference