I have a Windows 2012 R2 Essentials box I'm building (should be the same concerns as a Server 2012 or Server 2012 R2 box). I'm attempting to mirror the system disk (identical 750GB SATA drives) but I can never get a successful mirrored volume created!

How I do it:

  1. In Disk Management, right-click on my system disk (a single partition) and chose Add Mirror...
  2. Chose my second drive (it was Online and Unallocated)
  3. It gives me the prompt about not booting other boot volumes on dymanic drives and I click through that.
  4. Within a few seconds, within the first screen refresh that shows the mirroring, both drives are immediately in a "Failed Redundancy" state. They NEVER make it to the "Regenerating" or any other seemingly-valid state.

At this point, the event log gives me an Event ID 142:

Extent Disk2-01 on disk {guid} that is part of the fault-tolerant volume C: is no longer accessible.

  • both disks are Online
  • the second disk works just fine as a normal individual drive
  • both disks pass typical SMART tests
  • both disks pass extended tests from manufacturer utilities
  • using the Reactivate Volume option doesn't change anything
  • removing and recreating the mirrored volume doesn't change anything

I don't know what else to do to get this software RAID1 setup. Help!

  • 2
    There is a complete guide for setting up Disk Mirroring on Windows 2012 at blogs.technet.com/b/tip_of_the_day/archive/2014/10/10/… Mar 23 '15 at 7:58
  • @Panagiotis I think this is what I was looking for too. I am a little confused at how you can have a mirror drive that you have to update manually though! That concept seems crazy! Is "Disk Mirroring" not the same thing as a software raid? If so why would it tell you that "when you install updates you need to manually install them on the mirrored disk"... Going to try it and see what happens anyway. :)
    – Arvo Bowen
    Sep 2 '15 at 2:55

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