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Mirroring the OS


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Thanks for the advice which I agree with. As a newbie, I think you know what is coming next! :)

How do I carry out your 2 things mentioned above? I have recovered a client PC previoulsy and that worked fine

but I have never carried out what you suggest and would welcome some help on the best way to do them.


With the weekend coming up, I will have the time to carry these tests out.


Thanks in anticipation :D

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  • jmwills


  • ikon


  • Joe_Miner


  • Carpediem


  1. to test a mirror, just shut down the system and remove 1 of the drives. Then, boot the system back up -- it should detect that a drive is missing and declare that the mirror is degraded.

        I believe it's necessary to break the mirror manually but, because WHS2011 is based on Server 2008, there are some special instructions: http://support.microsoft.com/kb/969749. These instructions aren't 100% for a missing drive, but I believe they should be applicable for the most part.

        After breaking the mirror, shut down the system again, install a replacement drive and boot up again.

        Go back into Disk Manager and re-establish the mirror.


  2. to test the backup, shut down, replace the OS drive with a spare one, put your WHS2011 install DVD or USB stick into the system, boot up from it, and choose the Recovery option.

There are some caveats I highly recommend:

  1. never mess with your master OS drive. Put it to the side and work with spare drives. That way, you always have a way out if you paint yourself into a corner.


  2. do the backup & restore test first. That way, you have another valid boot disk available. Use it to establish your mirror and do the mirror test


  3. don't use the same mirror drive that you took out of the system as the replacement mirror drive -- use a different, blank drive.


  4. disconnect all your data drives while testing; no need to take any chances with them.

In reality, you should only need 2 spare drives: one to do the restore test, and a 2nd to mirror to the restore test drive.

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Thanks for the advice. A few final questions before I take the plunge if I may please.


  1. For the mirror test, is my sequence below correct?
  • Shutdown server and take out one of the mirrored OS drives
  • Server should boot up and declare that the mirror is degraded
  • Break mirror on the single drive I have just booted from using instructions you kindly linked above
  • shut down server and install a blank disk
  • Re e-stablish mirror in Disk Manager

In relaiton to the restore test

  • My current OS drives are 250gb. I have two spare 1TB disks which I can use here. Will this affect the restore process if the disk I'm restoring to is bigger than the original?
  • I have backups on an internal disk and also a USB3 (via PCIe card) external drive. Is it best to use the USB drive for the restore process or can I use the internal drive. The internal one has no data it is purely used for back up
  • All my data is on 2 x mirrored 2TB drives. If I remove them as you say will this affect the mirror? Is it best to Break Mirrored Volume first?

Many thanks

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1. looks good to me.


The fact that your spare drives are 1TB shouldn't be a factor. The extra space should just show up as unallocated in Disk Manager.


I think you may have to use the internal disk as the source for your OS backup. I don't think the WHS2011 installer knows how to use a USB3 drive out of the box.


I don't think you need to do anything special with the mirrored data drives; just unplug them. I would not break that mirror; only break the OS mirror. After all the testing is complete, you should be able to plug them back in and go. Now, having said that, I really hope you have a backup of them (remember, RAID: i.e. mirroring, is not a backup).


The #1 rule is never do anything to your system if you don't have a way to back out. With data, that means plenty of backup on hand :)

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Thats excellent thank you.


I fully get your a mirror is not a back up. I will have a backup on my external USB and also on the internal drive.


Wish me luck and I'll report back once I've done it. :unsure:

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Hi Ikon

I'm so glad you got me to test everything as I have failed on both counts!!!

Before I tell you what happened, could you tell me how I upload photo's as  took pictures

of the error messages etc but cannot figure out how to upload them.


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As far as testing everything is concerned, all I can say is bitter experience is a great teacher. :wacko: 


To upload photos, you click on your username (at the top right of the screen) and select My Gallery. Once in My Gallery click on an album on the right side (I believe there should be a default album under you username there). Once in the album, there is a large, black button labelled Upload on the right side. Click that button and you'll be taken to the Upload page, where you can browse for images on your computer and upload them.

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Thanks for the advice re uploading the photos. I'm not sure I've done it right as all I seem able to do is paste links to the photos rather than the photos. I hope you can see them!!

So below are the steps I took and the outcome of those steps:


Backup and Restore

  • I backed everything up to my internal back up drive and then my external back up drive
  • Shut down the server
  • Removed my data disks and mirrored OS disk from the bays. My other mirrored OS disk is under the ODD drive so I just unplugged the SATA connector to it rather than take the server apart.
  • Inserted a blank 1TB disk into bay 3 (counting from the left being bay 1). So all that was now in the server is my 3TB internal backup drive and a blank 1TB drive.
  • Booted from WHS 2011 DVD and it gave me the two options shown below. I chose restore.


  • The wizard then started looking for suitable backups and came up with the error message below. I tried this again with the same result.


  • I shut down the server and removed my 3TB internal back up disk and connected my external USB disk which I use for offsite backups and which I had backed up to before starting this process.
  • Everything as before but this time it found the back up on the attached USB disk


  • Following the wizard, I then ticked the ‘Only restore system drives’ as below.


  • Selected next and it stated it had started to restore and then the error message below appeared.


  • Tried the same again and got the same message.

 So in summary, tried with internal back up disk and external back up disk and both failed!! Any ideas welcome.



Phase 2: Test the OS mirror

  • Everything was backed up and returned to normal following my previous test above.
  • Removed one of my mirrored OS drives leaving just one OS drive in the server which is the one under the HDD drive mentioned above.
  • System took about 1min longer to boot but it did boot fine.
  • Went to disk manager and saw the picture below



  • You can clearly see disk 2 showing Failed Redundancy and Missing for the disk I took out
  • At this point, I tried to follow the intructions from this link http://support.microsoft.com/kb/969749 which I have listed below:


The boot mirror can be broken from DiskPart.exe using the following steps:

  1. From an elevated Command Prompt, type diskpart to start DiskPart.
  2. Use the list volume command in DiskPart to list the volumes present on the system.
  3. Type the command select volume x to select the mirror volume, where x is the alphanumeric identifier of the mirror volume.
  4. Determine the numeric identifier of the disk containing the plex you are currently booted into ("Boot Disk") using the list disk, select disk, and detail disk commands.
  5. Use the command break disk=n to break the mirror, where n is the numeric identifier of the disk containing the mirror plex you are not currently booted from.
  6. The mirror will be broken, and both plexes will be converted to Simple volumes.
  • So I successfully followed the above to point 4
  • At point 5 above, I took to read that I needed to insert the ‘n’ of the disk that I was not booting from i.e. the disk that was missing. But as it was missing it had no number!! At this point I felt out of my depth and abandoned!! The below is what I saw in CMD prompt. You can clearly see volumes 0,1 and 3 are the mirrored disk that is in the server but I cannot see anything for the missing disk! Any guidance welcome. :wacko: 


  • I then re-inserted the mirrored OS disk that I had removed. The server booted fine and the Mirror it showed in Disk Manager as failed redundancy.


  • I then right clicked the relevant volumes and selected ‘Reactivate Volume’. This then re-synched the mirror and all was well

So a very unsuccessful Sunday morning in the fact that I did not achieve the outcomes but very successful in the fact that I haven’t sat blindly until an inevitable problem comes and I find I have lost my OS or worse my data.

So now I turn to those with far greater knowledge for some assistance to either problem please. :blink: 

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One suggestion. I've had trouble restoring as well, if the drive I'm restoring to has partitions on it. The restore program gives you the ability to get into Disk Manager and delete the partitions, does it not? If so, I would try that. If it doesn't give the ability to get into Disk Manager then connect the drive to another computer and blow away the partitions. The best way, I feel, is to use DiskPart's Clean command.


This, BTW, is why I suggested restoring to spare disks and to never work with the original OS drive. You don't want the restore to get part way through restoring to your only working OS drive and then fail. It's also why it's good to clone your OS drive before experimenting like this.

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