Unmirroring

A mirrored device can be unmirrored in several ways. You can switch to the mirror device while retaining the original device; replace the original device with the mirror device, pause mirroring, or stop mirroring and remove the mirror device.

You use SQL Enterprise Manager to unmirror a device while editing an existing device. For more information about editing devices, see Chapter 5, Managing Devices.

    To unmirror a device

1. While editing an existing device, choose the Mirroring button from the Edit Database Devices dialog box.

   The Unmirror Device dialog box appears.

   

2. Select one of the mirroring options:
   • To switch to the mirror device while retaining the original device, select Switch to Mirror Device¾Retain. If you select this option, you can later change back to the original device and continue mirroring.
   • To replace the original device with the mirror device, select Switch to Mirror Device¾Replace.
   • To pause mirroring, select Turn Off Mirroring¾Retain Mirror Device. If you select this option, you can later remirror the device.
   • To stop mirroring and remove the mirror device, select Turn Off Mirroring¾Remove Mirror Device.
3. Choose OK.

If a device is mirrored and one of the two devices fails, the device is automatically unmirrored. If the mirrored device is the one that fails, you can unmirror the mirror and then replace the failed device with the mirrored device.

When you stop mirroring and remove a mirror device, the device is removed but the physical file still remains. You must delete the device's filename from the directory where it is located, using the operating-system del command. It is not necessary to shut down and restart SQL Server.

Mirroring can also be stopped using the DISK UNMIRROR statement. For information, see the Microsoft SQL Server Transact-SQL Reference.