I'm running Windows Server 2008 R2 and converted physical disks to dynamic disks and combined them to a spanned volume. Yesterday, one disk started throwing S.M.A.R.T Errors, so I decided to get a new disk to replace it.

Now, I installed it to my system, converted it to a dynamic disk and made it part of the spanned volume. My Question is: How can I remove the old disk from the spanned volume, without losing data?

  • 2
    I hate to say it but this would have been a great time to ask what a spanned volume did before configuring the new disk as part of one.
    – Rob Moir
    Mar 23 '11 at 11:48
  • You mean, if the disk just fails from one to another second? I'd then say, all data on that disk is lost. You have to add a new disk to the spanned volume and restore the backup. I never tested it, but that would be my scenario in that case.
    – Kuckucksei
    Mar 23 '11 at 12:43
  • 1
    Seriously, you need to stop and go and read up on what a spanned volume is. You clearly didn't understand it when you chose that option and you clearly don't understand it now. A spanned volume is a partition that has been "stretched" across two disks. If either one of those disks fails then ALL data on the partition, that is data from the spanned volume regardless of what disk they are on, is lost...
    – Rob Moir
    Mar 23 '11 at 13:53
  • 4
    There is nothing safe about a spanned volume. You use it because you're desperate to extend space on a disk any way you possibly can and to hell with the consequences (or you're doing something very clever with hardware RAID and even then I'd frankly still be reluctant), not because its a great idea.
    – Rob Moir
    Mar 23 '11 at 14:18
  • 2
    I think the problem here is a fundamental misunderstanding of how a spanned volume works. When you span volumes in Windows, you're simply combining hard drives' space to make one big storage area. Bits A, B, and C are on HD1, and bits D, E, and F are on HD2. If you remove HD1, then bits A-C are simply gone. There is no redundancy built in, and HD2 has no way to magically recognize that you're missing bits A-C.
    – Hyppy
    Mar 23 '11 at 14:38

So it's just a plain old spanned, non-RAID-protected, volume right?

If, well you'll have to backup the entire volume, replace the disk, rebuild a blank new spanned volume and restore your data.

Essentially you have no easy way to do this, consider using some from RAID other than spanning's effectively R0 setup.

  • I could restore the latest backup, but it's not really elegant. I mean the process for safely removing a disk can't be very complicated. It has just to move all files from the old disk to the other disks in the volume...
    – Kuckucksei
    Mar 23 '11 at 12:37
  • 1
    What's not elegant? Restoring the latest backup? Why does it need to be elegant? I don't expect my backups and restores to be elegant, but I do expect them to work and I test them to verify that they do.
    – joeqwerty
    Mar 23 '11 at 12:54
  • I just thought there is an elegant way to do it. Because the process doesn't seem to be complicated. Don't get me wrong: It's OK for me to just restore the backup.
    – Kuckucksei
    Mar 23 '11 at 13:05
  • Using the backups is the elegant solution. Why would you want to risk corrupt data from a disk that is failing?
    – JamesRyan
    Apr 24 '14 at 11:06

I've tested this on Windows Server 2012 R2. I had a 3TB spanned volume over three 1TB disks.

I just shrinked the 3TB spanned volume to 2TB in Disk management. This made all the space on the last disk unallocated. After this I was able to remove the disk without losing any data.

Unfortunately this solution will not work if you want to remove the first disk from the spanned volume.

  • This works fine in Windows Server 2012 R2. Feb 18 '16 at 13:18
  • 1
    Also works in Windows 10 as well. If you want to monitor the progress of the shrink or stop it it, then open the Disk Defrag UI (Optimize Drives) window. Mar 6 '16 at 5:35

Actually, for those interested in an answer besides "don't": I found this: http://richardbenson.co.uk/2008/10/removing-a-drive-from-a-spanne/

This seems to be the general method:

  • Make sure there is enough free space to be able to remove one of the disks.
  • Defrag the disk using jkdefrag to move all data to the start of the volume.
  • Remove any crap that the defragging didn't, manually.
  • Use the disk manager to "shrink" the spanned volume.
  • Rebuild the partition table on the disk that has been shrunk out.

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