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Oracle® Database 2 Day DBA
10g Release 2 (10.2)

Part Number B14196-02
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Dropping Disks from a Disk Group

When you drop a disk from the disk group, the disk group is rebalanced by moving all of the file extents from the dropped disk to other disks in the disk group. ASM then releases the disk, and you can then add it to another disk group or use it for other purposes. You can drop one or multiple disks in a single operation. You can also optionally set rebalance power for the drop operation.

The following is a list of possible reasons for dropping a disk:


Dropping disks from a disk group only logically deletes the disks from the disk group. It does not delete the disk contents. However, the contents are lost when you add the disk to a new disk group.

To drop one or more disks from a disk group:

  1. Access the ASM Home page.

    See "Accessing the Automatic Storage Management Home Page" for instructions.

  2. Click the Administration tab.

  3. If the Automatic Storage Management Login page appears, log in as the SYS user, connecting as SYSDBA. Provide the SYS password that is stored in the password file for the ASM instance. This password was set up when the ASM instance was created.

  4. On the ASM Administration page, under the Disk Groups heading, click a link in the Name column to select the disk group from which you want to drop disks.

    The Disk Group page appears.

  5. Under the Member Disks heading, in the Select column, select the check boxes for the disks that you want to drop, and then click Remove.

    A confirmation page appears.

  6. If you want to change rebalance power, or if you want set the FORCE option for dropping disks, do the following:

    • Click Advanced Options.

    • On the Advanced Options page, optionally select the FORCE option or select a rebalance power in the drop-down list.

    • Click OK to return to the confirmation page.


    You may need the FORCE option if ASM cannot read from or write to the disk. See Oracle Database Administrator's Guide for more information on the FORCE option.
  7. Click Yes to drop the disks.

    The Disk Group page returns, and displays a state of DROPPING for each disk being dropped.

  8. Refresh the page until the dropped disks no longer appear in the disk group.


You cannot reuse or disconnect the dropped disks until the drop and rebalance operations are complete—that is, until the dropped disks no longer appear in the disk group. See Oracle Database Administrator's Guide for more information, and for other caveats for dropping disks.