Replace a failed mirror with a new mirror on another disk

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

To replace the failed mirror with a new mirror on another disk

If the disk containing part of the mirrored volume is missing and the volume does not return to Healthy status, you should replace the failed mirror with a new mirror on another disk.

  • Using the Windows interface

  • Using a command line

Using the Windows interface

  1. Open Computer Management (Local).

  2. In the console tree, click Computer Management (Local), click Storage, and then click Disk Management.

  3. Right-click the mirror on the Missing or Offline disk, and then click Remove Mirror. Follow the instructions on your screen.

  4. Right-click the volume to be re-mirrored, and then click Add Mirror. Follow the instructions on your screen.

Important

  • Before installing a new disk, break the mirror and then examine the system log to see if the disk or the disk controller is failing. If the failing mirror is on a controller that is failing, installing a new disk on the failing controller will not solve the problem. For instructions describing how to open Event Viewer to examine the system log, see Related Topics.

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.

  • To replace a mirror in the mirrored volume, you must have a dynamic disk with unallocated space that is at least as large as the region to repair. If you do not have a dynamic disk with enough unallocated space, the Add Mirror command is unavailable. (To verify you have enough space, right-click the disk, click Properties, and then check the size in Unallocated space. This size may be slightly smaller than shown in the graphical and list views.)

  • If you are replacing one of the disks in a mirrored system volume, be sure to use an identical disk to the one you are replacing. Otherwise, startup problems might occur if the disks use different geometries or if the system volumes are at different offsets on the disks. Always test your configuration by attempting to start the operating system from each volume to ensure that the operating system can actually start if one of the disks fails. For more information about mirroring the system volume, see "Disk Management" at the Microsoft Windows Resource Kits Web site.

Using a command line

  1. Open Command Prompt.

  2. Type:

    diskpart

  3. At the DISKPART prompt, type:

    list volume

    Make note of the volume number of the mirrored volume.

  4. At the DISKPART prompt, type:

    select volume n

  5. 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.

  6. At the DISKPART prompt, type:

    break disk n [nokeep]

  7. At the DISKPART prompt, type:

    select volume n

    Select the volume that contains the volume you want to mirror.

  8. At the DISKPART prompt, type:

    list disk

    Make note of the disk number of the dynamic disk on which you want to mirror the volume.

  9. At the DISKPART prompt, type:

    add disk n

Important

  • Before installing a new disk, break the mirror and then examine the system log to see if the disk or the disk controller is failing. If the failing mirror is on a controller that is failing, installing a new disk on the failing controller will not solve the problem. For instructions describing how to open Event Viewer to examine the system log, see Related Topics.
Value Description

list volume

Displays a list of basic and dynamic volumes on all disks.

select volume n

Selects the specified volume, where n is the volume number, 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.

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.

list disk

Displays a list of disks and information about them, such as their size, amount of available free space, whether the disk is a basic or dynamic disk, and whether the disk uses the master boot record (MBR) or GUID partition table (GPT) partition style. The disk marked with an asterisk (*) has focus.

add disk n

Mirrors the simple volume with focus to the specified disk. The specified disk must have unallocated space at least as large as the size of the simple volume you want to mirror.

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.

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.

  • To replace a mirror in the mirrored volume, you must have a dynamic disk with unallocated space that is at least as large as the region to repair.

  • If you are replacing one of the disks in a mirrored system volume, be sure to use an identical disk to the one you are replacing. Otherwise, startup problems might occur if the disks use different geometries or if the system volumes are at different offsets on the disks. Always test your configuration by attempting to start the operating system from each volume to ensure that the operating system can actually start if one of the disks fails. For more information about mirroring the system volume, see "Disk Management" at the Microsoft Windows Resource Kits Web site.

  • For more information about DiskPart, see Related Topics.

Information about functional differences

  • Your server might function differently based on the version and edition of the operating system that is installed, your account permissions, and your menu settings. For more information, see Viewing Help on the Web.

See Also

Concepts

Using the Event Viewer snap-in
Event Viewer overview
View an event log
Using mirrored volumes
Disk status descriptions
Volume status descriptions
Troubleshooting Disk Management
Working with MMC console files
DiskPart