Related:How to Use Windows 10’s Storage Spaces to Mirror and Combine Drives
Windows 8 or 10?
Use thenew Storage Spaces feature instead.
This makes it easy to turn your existing spare hard drives into massive storage or even redundant backups.
When computer management opens press disk management on the left side.
Once they are deleted you should only be left with disks you do not want included in the RAID.
Instead they use spanned, striped, and mirrored as the options for creating software RAIDs.
Thanks to the commenters for pointing that out.
In both cases there is no redundancy so it’s crucial that you create your own backups.
Right press the first disk you want included in your RAID and select new spanned volume.
This will open up the New Spanned Volume Wizard in Windows.
Click next and then select which disks you want included in your new volume (a.k.a.
Assign the new volume a mount letter or mount point.
Name and format the volume and click next.
