Virtualbox: inaccessable VMs?

Question

I have two inaccessible VM's here, I'm entirely unsure of how to resolve this issue, and don't want to mess up any of my files.

I found a thread on the internet about this, but it's specific to Windows. I'm using Ubuntu.

I have taken multiple snapshots, there is one minutes before this failure occurred, is there a way I can restore these VMs?

These are the most recent snapshots for each machine:

This problem started when backing up during a power failure, so my guess is that the most recent snapshots that are being loaded are uncompleted and leading to this issue.

What should I do to resolve this? Is there a tool? Is there something I must manually edit from the XML file and files to delete? (xml file for "devubuntu": http://pastebin.com/KhL9831v )

Answer 1

The answer is to correct the XML document.

For example, with the DevUbuntu VM, it is failing to load for {cfc46381-ba33-462a-b1e5-426541791c40}, which only occurs once in the document, towards the end:

<StorageControllers>
  <StorageController name="IDE Controller" type="PIIX4" PortCount="2">
    <AttachedDevice type="HardDisk" port="0" device="0">
      <Image uuid="{cfc46381-ba33-462a-b1e5-426541791c40}"/>
    </AttachedDevice>
  </StorageController>
</StorageControllers>

This is the drive it's trying to load, which did not successfully generate it's own backup snapshot but ended up being modified into the XML anyway. The fix is to replace this UUID with the last working image, if you're unsure, replacing it and clicking "refresh" from the VM manager will either give you this error or, if you have the right image, not give an error (and in my case, on windows 7, close the manager).

You can then launch the VM, and take another snapshot as normal.

Advice: Backup your XML files when doing snapshots.

Answer 2

From How to: Create and manage snapshots in VirtualBox :

To revert your current machine to a previous snapshot, open VirtualBox, select your virtual machine and click on the Snapshots tab. Right click on the Current State icon and select Revert to Current Snapshot, which will bring the virtual machine back to the latest snapshot you took.

However, read first this article : The VirtualBox Snapshot Manager Sucks.
It contains some warnings that you should take very seriously.

I suggest taking first a complete backup of your VM, which is also not a simple task.