virtualbox.org

Host: Windows 8.1
Guest: Windows XP
Oracle VM VirtualBox 4.3.6

The guest system was working fine (so it was on) when a power outage occurred. When I restarted Windows 8.1 and tried to run again the guest on Oracle VM VirtualBox, it got to the point where the XP logo was on the screen and the progress bar showed, but then it got to a bluescreen error, then restarted with Windows XP start options (Safe Mode, last working configuration, Normal etc). No matter which variant I choose, it goes to the same loop. The BSOD is so quick that I had to film it. It says UNMOUNTABLE_BOOT_VOLUME and error 0xED.

Nothing else was added to or removed from the system. It happened just as I restarted the host.

Is there a way to repair that? It is kinda important to me.

Is the XP guest boot process entirely standard? I.e. no grub, no dual boot etc?

The first thing to notice is that the error is happening in the guest, meaning VirtualBox is still happy with the VDI file.

A power outage will cause loss of data, but that shouldn't affect parts of the (virtual) disk already written, i.e. the boot sectors. So, provided you aren't using snapshots this shouldn't have caused a problem.

Thank you for the reply. Actually, I am not very knowledgeable about VirtualBox and virtual machines.
The XP boot is indeed "standard", no funny tricks.
I'm not sure about any snapshots.

That said, how should I begin to repair it? Are there specific steps?

Before doing anything else I would make a backup of the VM folder so things can't get any worse.

Then I would read the Microsoft Support article: Unmountable Boot Volume. Of course you can ignore the various hardware suggestions: you need to be thinking about booting from a (virtual) repair CD, or mounting the disk in another Windows VM - and running chkdsk on the damaged filesystem. You might also need to run fixboot.

In future you should consider making backups of your VM on a regular basis. If you had a recent backup this would be a trivial problem.

As I said, I know very little about VirtualBox and virtual machines. Therefore, your suggestions make little sense to me.

How could I boot from a CD? I'd be running Windows 8.1 as a guest and when I start the host XP, there is no option to change the boot order. It's not like I have access to some internal XP BIOS or something. Besides, once inside the loop, there is no way out.

I have no idea how to build a virtual repair CD.

I have no idea how to "mount the disk in another Windows VM". What other VM? I only have that one.

How to run fixboot (or anything) when I'm in a no-escape loop?

Would you (or anyone) try to explain a step-by-step procedure in accessible terms? Obviously if I had been an expert in VM, I wouldn't have needed help.

You boot the guest from a virtual CD, not the host. Think of the host as a separate PC - it's almost never relevant to the discussion.

As to how to boot a VM from a (virtual CD) you do it by attaching an ISO image to the virtual CD drive which is shown the Storage settings of you VM, and it's also worth checking the System part of the VM settings to make sure the CD comes first in the boot order.

"Mount the the disk in another VM" == create another VM, mount the disk in it.

"How to run fixboot"... As already described, you boot from a recovery CD, with fixboot on the CD. Or, run it from the other VM.

I'm afraid that I can't give you general Windows tuition. This is a VirtualBox forum - you're expected to understand the basic PC stuff already, otherwise VMing is kind of running before you can walk. Did someone else set up this VM for you? If you so might perhaps ask that person to help.

Would someone else try to respond in a more straightforward way? This respondent seems to think that everyone is an expert in VMs. Then why the forum?

Working with VMs is not basic PC knowledge.

Besides, I only have the host (Win 8.1 ) and the guest (Win XP). I have no boot CD (virtual or non-virtual), no ISO image. I don't even have access to the original XP system.

How is it possible to mount a disk on another VM, since that disk is only virtual and not accessible but via the VM that is broken?

Can anyone on this forum provide a step-by-step procedure?

Read the Manual. Chapter 1. First steps. Then read it again. I hope this is clear.

For a Windows XP Guest:

1. In the Oracle VM VirtualBox Manager, select the faulty XP guest and go to Settings/System and make sure the CD is above the Hard Disk in the Boot Order.

2. Insert the Windows XP installation CD and launch the virtual machine.

3. If you get a message like “no bootable medium found”, the the virtual machine has interpreted another virtual device as the CD drive, so right-click inside the window (or press CTRL+HOME) and correct that, by choosing the real CD drive. Restart.

4. Wait until it gets you to the welcome screen, then hit the R key on your keyboard. It will enter the recovery mode with a DOS prompt.

5. Now type chkdsk /p and hit Enter. This will launch a utility which will check for errors on your hard drive.

6. After the process is done, type fixboot and hit Enter to repair any damaged boot files which may have become corrupted. When asked to say yes or no, type the Y key on your keyboard.

7. Type exit and press the Enter key to reboot your computer (after extracting the installation CD).

If the virtual machine still doesn’t work, then it might be irreparable.