I'm interested in rebuilding a basic degraded dynamic volume without resorting to trivially breaking/deleting and re-creating the volume.

There is no concern about data loss. I hope to use this as a learning opportunity to better understand Windows dynamic disks/volumes.

The situation: A dynamic volume under Windows 8 consisting of two physical drives in a mirror configuration has been running in degraded mode. The first plex of the mirror volume is labeled by Windows as "Failed Redundancy". The former entry for the second plex of the same volume remains and is labeled as "Missing". I suspect that the fault was interruption of power to second device (the drive cage has some chintzy power switches for each drive). Attempting to reactivate the volume yields the error message The plex is missing. This is a little surprising as the second disk is recognized by the system. It has a recognized dynamic volume, but is labeled "Foreign" and displays no detail about the volume (which is more or less consistent with the error message).

The Disk Management console has an option to "Import Foreign Disks," but it is not clear what effect it will have. Early in my search for information I read an account that this will import contents as new distinct volumes rather than reconciling with existing volumes. What will this action do?

Is there a Windows equivalent to Linux's mdadm to manually manipulate dynamic volumes or at least get a better sense of how Windows conceptualizes these devices?

  • 3
    Did you solve this? – tholu Jul 27 '16 at 14:05

"Import Foreign Disks" did not reassociate (rebuild) the degraded volume. I believe the foreign disk was no longer marked as "Foreign", but the first plex remained as "Failed Redudancy" and the second plex "Missing".

There weren't any other actions available in the management interface, so I ultimated deleted and re-created the volume.


This solved the same issue for me:

  1. Open Administrative Tools, Computer Management, Disk Management.
  2. Right click on your mirrored volume and select Remove Mirror.
  3. Remove the disk that has failed -- do not remove the sole remaining good disk.
  4. Ensure that your new replacement disk is setup as a Dynamic Disk.
  5. Right click again on the volume and this time select Add Mirror.
  6. Select the new replacement disk.
  7. Allow the resynch to finish.

Not the most intuitive sequence of actions, but it works.

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