I have a computer with one system disk (running Windows 10) and six data disks. I have created a Storage Space using the six data disks. However, it seems that not one but two disks are used as fault tolerance, which I think is a bit too much.

Can anyone tell me why - or just how to change this?


  • Storage Spaces is virtually a software RAID. In this particular RAID design there is fault tolerance. In your specific case your RAID requires 2 disks for fault tolerance. If you want less fault tolerance, use a hardware RAID, sounds like you actually just want to use JBOD instead any of the RAID levels. Storage Space does allow you to set "mirroring, parity, or no redundancy on a folder-by-folder basis". The article is about Windows 8 but it applies to Windows 10. – Ramhound Apr 28 '16 at 14:01
  • But how come my specific case requires two disks for fault tolerance? I found this article that specifies that parity requires a single disk for fault tolerance: "Parity: Windows stores parity information with the data, protecting you from a single drive failure. Parity uses drive space more efficiently than mirroring, but file access times are slower. Parity is ideal for drives with large, infrequently updated files, such as video files." – xavis Apr 28 '16 at 14:16
  • The amount of parity drives depends on the amount of data drives you have. I linked you to THE article that explains how Storage Space works. Anyways you created your Storage Space with 2 disks, you can create it with less, but the amount of partity would be half. I based that statement on the assumption all disk are equal size, since you provided no information, I can't post an answer. – Ramhound Apr 28 '16 at 14:18
  • Alright, cheers - will look into it when I'm off work. – xavis Apr 28 '16 at 14:21

We managed to do it by first creating a Storage Space comprising all six disks. Then, without entering drive size and formatting the drive, we used powershell to create a virtual drive, set the correct size and the ResiliencySettingName to Parity and the PhysicalDiskRedundancy to 1.

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