I've recently started trying to use VirtualBox for my new machine so I can prevent the base OS from any artifacts/etc.

I've created a Base OS and removed the drive, marked it as immutable, and created another for development, attached that drive, made a snapshot, changed the drive to the snapshot and marked the snapshot so it won't clear each time.

I haven't got in my UI, however, the checkbox that flags it as a differencing disk - I'm assuming it is one because I am attached to the snapshot and it is saving each time, etc.

The problem is, I made my Base OS install 20gb, and now with all my dev tools, my differencing disk has filled that - and although everything I google about it says that a snapshot will just keep growing (and I made my original disk to keep growing before making it immutable), it is telling me I am out of room trying to copy new files on it.

Is there a way to make the differencing disk auto-grow/set the size larger than the Base OS immutable disk I started with, or have I missed something?


I think you have misunderstood the original VirtualBox configuration option. When you create a virtual disk in VirtualBox and you set it to dynamically grow, it will only take up as much space on the actual disk as it needs to, and it will grow to the limit you defined as the maximum disk size. You have now reached that maximum size and that's why you are getting these error messages.

Unfortunately there isn't really any way out of this other than creating another, larger, virtual disk, copying all your snapshot data across and then using it. Whether or not this is actually feasible depends on whether the OS you are using will support this process (and you haven't told us what OS that is).

  • Apologies - I've been using Win7. Since it was my first day creating the VMs I blew it away and recreated with a very large limit, and figured since it grows and doesn't reserve that I was safer doing that. – crucible Jun 7 '11 at 23:04
  • you can resize the vdi from the command line – Muad'Dib Jul 22 '11 at 14:57

you can resize the vdi with a command line like this: "C:\Program Files\Oracle\VirtualBox\VBoxManage" modifyhd "myvdi.vdi" --resize "somesize"

it should also be noted that you will have to remove the vdi from the virtual box manager, otherwise modifyhd command will give you errors. dont worry, though, you just re-add the newly resized vdi when you are done.

where myvdi.vdi is the name and path of the vdi you want to resize and "somesize" is the size in megs that you want.

after you resize the VDI, you have to resize the partion for windows to utilize the new space. you can do this by getting a "live" gparted image.

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