On my Hyper-V R2 virtual platform, I'm often using differentiating disks to preserve disk space.

Basically, I have this hierarchy of differentiating disk :

  • OS 1.vhd
    • Dev platform.vhd
      • User 1 dev computer.vhd
      • User 2 dev computer.vhd
    • Production platform.vhd
      • Server 1.vhd
      • Server 2.vhd


this is great for saving space, at the creation time.

Several month later, a lot of updates, maybe service pack can have been released. As parent disks does not allow to be changed, is there a way to "rebuild" the hierarchy ?

More precisely, if I have "X" vhd files, can I "extract" one parent VHD file with all similar files (binary, ACLs, etc.) and X differentiating disks ?


Problem is Hyper-V was not designed to do this and you've run into the limitation of the design. A tool like Parallels Virtuozzo is more suited to your use case where the underlying OS is constant and VMs maintain there own differences.

  • I've never taken a look at parralels. When you say the OS is constant... what do you mean ? I can apply an hotfix of the OS once for all ? (PS: just curious... moving from hyper-v to anything else is not possible today) – Steve B Aug 31 '11 at 12:30
  • Could you explain in more detail how Parallels is different from Hyper-V? I don't see how you could upgrade a parent image and have it gracefully cascade to the children. – Chris S Aug 31 '11 at 12:34
  • I should have said Parallels Virtuozzo (answer modified). Virtuozzo does OS virtualization not hardware vz. More here: parallels.com/products/pvc46/info/virtualization – uSlackr Aug 31 '11 at 12:38
  • I'm sure to understand what you mean. I wasn't wishing to do that in real time, but I want to do this once, allowing to shut down the VM. And moreover, I only want to work with the virtual hard drive... used by a VM, this does not matter. – Steve B Sep 1 '11 at 7:55

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