I have three 10TB hard drives labeled as D:, F:, and G: respectively. Each of them has some free space available at the end of the drive. There are no OSes installed on any of the drives and keeping the data that is on the drives must be kept intact. I cannot format or lose the data on these drives. I unfortunately have no way of backing up this data at the time of writing, but that's a separate issue.

The available space is as follows:

D: has 89.6GB available F: has 89.7GB available G: has 89.9GB available

What I would like to do, if possible, is combine the available space from all 3 drives into one "virtual" drive with it's own drive letter (i.e. drive J: with a total of 269.2GB) without having to format the disks. I'd like to keep the data as-is and only work with the free space at the end of the drives.

I am not quite sure how to go about doing this or if I even can. Any help is appreciated. Thank you.

  • 2
    I'd suggest very seriously thinking again before playing with 30TB of no-backup data for the gain of 300GB.
    – Tetsujin
    Jun 30, 2021 at 12:48
  • AFAIK, Windows doesn't support this (see VHDX and About VHD)
    – JW0914
    Jun 30, 2021 at 12:57
  • This is a disaster waiting to happen. Don't do anything before figuring out your backup strategy.
    – gronostaj
    Jun 30, 2021 at 13:00
  • I think it would be crazy to mess with any of those partitions but something that you might consider is adding partitions to fill those spaces and mount those (via junction or soft link) somewhere useful. I am with everyone else here.. you would be nuts to screw with all of that data.. in fact.. I wouldn't even do the first thing I mentioned.. but that would be lower risk than what you are asking about. Jun 30, 2021 at 14:04
  • Fair enough. Thanks for the suggestions. For giggles, COULD this be done?
    – Grimace
    Jul 1, 2021 at 0:45

1 Answer 1


Sure it’s possible, quite easily so. Windows 10 still supports Dynamic Disks, a sort-of predecessor of Storage Spaces. It’s very similar to Linux Logical Volume Manager (LVM).

There are many caveats:

  • Dynamic Disks are not well-understood by data recovery software
  • Dynamic Disks are not fully supported on Linux
  • The conversion is irreversible

The procedure would be somewhat like this:

  1. Go to Disk Management
  2. Convert all drives that should provide space to Dynamic Disks (via context menu)
  3. Create a new mirrored/spanned/striped/RAID-5 volume in the free space.

But really, don’t.

If you are truly set on utilizing the space, there’s also the possibility of letting third-party software handle it. One such software (sadly not for Windows) is MergerFS. It creates a unified view over multiple filesystems and uses sophisticated rules to decide where to write updates/new files.

I found one similar program for Windows, StableBit DrivePool, but have not tested it and as such cannot recommend it.

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