Steps to Recover a Failed Mirrored System/Boot Partition


The fault tolerance (FT) driver cannot initialize after a failure of a mirrored
boot partition (containing Windows NT system files) and system partition
(containing NTLDR and boot loader files). This kbarticle provides a step-by-step
system recovery procedure for such a failure : Q120227

A gotcha! when a mirror fails, the system boots when using a boot disk but
not by itself even when the boot.ini from the boot disk is copied to the system
partition.

The shadow disk, the surviving member of the mirror, the member that was not
the active partition, is missing the Master Boot Record (MBR). See Master Boot Record Not Written to Mirrored Shadow Partition
for background. NT mirroring does not duplicate the MBR. For the shadow to
be able to boot, it must have an active partition’s MBR. If you create a
partition on the drive to be mirror and make it an active partion, the correct
MBR will be created. You can then delete the partition and setup the mirror and
it will be able to boot.

You could try to rewrite it with “fdisk /mbr” from a bootable DOS floppy that
includes fdisk.exe, but there are potential problems. See Using FDISK /MBR for Troubleshooting Windows NT Boot Problems

A final possibility would be to use the low level disk editor, dskprobe.exe,
from the Resource Kit to copy a working MBR.

Another gotcha! occurs when you try to delete a partition that was part of a
broken mirror set, you receive this error message The drive
cannot be locked for exclusive use. Please check to see if some applications are
currently accessing the drive. If so, close them and try again.
This is
not exclusively a mirror issue.

Check to see if any of the conditions listed below apply as the standard
reason(s) for not being able to lock a volume:



  • A paging file is on the volume.
  • A program that was started from the volume is still running.
  • A program that’s running has loaded a .dll file from the volume.
  • A program has a file open on the volume.
  • A program’s current folder is on the volume.
  • A service has a lock on the volume.
Except for the paging file
issue, these can be eliminated by a reboot. If none of these apply, you can use
Disk Administrator to select the partition you wish to delete. Use Tools |
Assign Drive Letter To and then choose Do Not Assign A Drive Letter and click
OK. You should now be able to successfully delete the partition.

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