Remove a mirror from a mirrored volume

Applies To: Windows Server 2003, Windows Server 2003 R2, Windows Server 2003 with SP1, Windows Server 2003 with SP2

To remove a mirror from a mirrored volume

Open Computer Management (Local).
In the console tree, click Computer Management (Local), click Storage, and then click Disk Management.
Right-click the mirror you want to remove, click Remove Mirror, and then follow the instructions on your screen.

Important

Once you remove a mirror from a mirrored volume, the removed mirror becomes unallocated space and the remaining mirror becomes a simple volume that is no longer fault tolerant. All of the data on the removed mirror is deleted.

Notes

To perform this procedure on a local computer, you must be a member of the Backup Operators group or Administrators group on the local computer, or you must have been delegated the appropriate authority. To perform this procedure remotely, you must be a member of the Backup Operators group or Administrators group on the remote computer. If the computer is joined to a domain, members of the Domain Admins group might be able to perform this procedure. As a security best practice, consider using Run as to perform this procedure. For more information, see Default local groups, Default groups, and Using Run as.
To open Computer Management, click Start, click Control Panel, double-click Administrative Tools, and then double-click Computer Management.
You can only regenerate mirrored volumes with Failed Redundancy status. If the mirrored volume has Failed status, try to return it to Failed Redundancy status by using the Reactivate Disk command on the remaining disks.

Open Command Prompt.
Type:

diskpart
At the DISKPART prompt, type:

list volume

Make note of the volume number of the mirrored volume.
At the DISKPART prompt, type:

select volume n
At the DISKPART prompt, type:

detail volume

Make note of the disk number that specifies the half of the mirrored volume you want to remove and convert to free space.
At the DISKPART prompt, type:

break disk n [nokeep]

Value	Description
list volume	Displays a list of basic and dynamic volumes on all disks.
select volume n	Selects the specified volume and gives it focus. If no volume is specified, the select command lists the current volume with focus. You can specify the volume by number, drive letter, or mount point path. On a basic disk, selecting a volume also gives the corresponding partition focus. You can view the numbers of all volumes on the computer by using the list volume command.
detail volume	Displays the disks on which the current volume resides.
break disk n	Applies to dynamic disks only. Breaks a mirrored volume into two simple volumes. These volumes are no longer fault tolerant. The disk specified by n receives the focus so you can assign it a drive letter. If the specified disk is the current system or boot disk, the command fails. The other disk retains the drive letter and any mount points that belonged to the mirrored volume. Using the nokeep parameter, the specified disk, n, is deleted and converted to free space, while the other half of the mirror is retained as a simple volume. Neither volume receives focus.
Nokeep	Specifies that only one of the mirrored volumes retained; the other simple volume is deleted and converted to free space. Neither volume receives the focus.

Important

Once you remove a mirror from a mirrored volume, the removed mirror becomes unallocated space and the remaining mirror becomes a simple volume that is no longer fault tolerant. All of the data on the removed mirror is deleted.

Notes

To perform this procedure on a local computer, you must be a member of the Backup Operators group, Administrators group, or you must have been delegated the appropriate authority. If the computer is joined to a domain, members of the Domain Admins group might be able to perform this procedure. As a security best practice, consider using Run as to perform this procedure. For more information, see Default local groups, Default groups, and Using Run as.
To open a command prompt, click Start, point to All programs, point to Accessories, and then click Command prompt.
You can only regenerate mirrored volumes with Failed Redundancy status. If the mirrored volume has Failed status, try to return it to Failed Redundancy status by using the DiskPart online command on the remaining disks.
For more information about DiskPart, see Related Topics.

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