Differencing Image of Snapshot, Open Hard Disk Not Found

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Differencing Image of Snapshot, Open Hard Disk Not Found

Postby BeauB » 11. Apr 2012, 20:05

Afternoon ladies and gents,

I am receiving an NS_ERROR_FAILURE (0x80004005). Specifically:
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Failed to open virtual machine located in /Users/beau/VirtualBox VMs/Windows 7/Windows 7.vbox.

A differencing image of snapshot {0c66a857-5c78-42a9-8d91-d926b7509178} could not be found. Could not find an open hard disk with UUID {eb3697d7-1dab-4ba4-b3ef-a526fc2da1ac}.

Result Code: NS_ERROR_FAILURE (0x80004005)
Component: SnapshotMachine
Interface: IMachine {5eaa9319-62fc-4b0a-843c-0cb1940f8a91}
Callee: IVirtualBox {c28be65f-1a8f-43b4-81f1-eb60cb516e66}


This started because my company Mac got stuck in another state of throwing 2-3 kernel panics per day. After one hit during screensaver, system would not respond. I was able to salvage the data by booting off the second install...but I was not able to properly export it. Now I have a VDI file that works fine, but has reverted fresh install snapshot (without ANY of the recent work). When I try to add the .vbox file, I receive the error above. I am running OS X 10.6.8 (Snow Leopard) and the guest is Windows 7 x86.

Can anyone suggest anything to try and recover from this? :-\

-Beau
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Re: Differencing Image of Snapshot, Open Hard Disk Not Found

Postby mpack » 11. Apr 2012, 20:21

The error message means what it says: the snapshot chain references a hard disk whose UUID is "eb3697d7-1dab-4ba4-b3ef-a526fc2da1ac", and no such hard disk is registered with any currently registered VM. You might get this if one VM references the disks used by an older VM, and then you delete the older VM. This is only one of the great variety of possible ways in which snapshots can ruin your day.

I'm afraid there is little which can be done remotely. If you can find the missing file then you might be able to add it to the non-functioning VM. If the file has been deleted then you will need to restore it from a backup. If you don't have a backup then it's game over.

Even if you have a number of candidate files, you'll have the problem of verifying that it has the right UUID. In the case of files in "Snapshots" subfolders, these usually have names which match their UUID, so that would be easy if it was one of them. If it's a base VDI then the easiest thing is to look at it's header using the CloneVDI tool.
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Re: Differencing Image of Snapshot, Open Hard Disk Not Found

Postby BeauB » 11. Apr 2012, 21:30

I was afraid of that. I will rebuild the bloody thing.

Thank you very much for the answer.

-Beau
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Re: Differencing Image of Snapshot, Open Hard Disk Not Found

Postby haytham.med » 7. Jan 2014, 19:13

Hi
I got this too:

Failed to open virtual machine located in H:/Hay drive/vdi/Test2/Test2.vbox.

A differencing image of snapshot {c9e15a55-4722-4a72-9988-44138c191586} could not be found. Could not find an open hard disk with UUID {9f5f6518-7bd7-44d2-9b15-e72132ef4809}.

Result Code: E_FAIL (0x80004005)
Component: SnapshotMachine
Interface: IMachine {480cf695-2d8d-4256-9c7c-cce4184fa048}
Callee: IVirtualBox {fafa4e17-1ee2-4905-a10e-fe7c18bf5554}

I attached a swap partition to 2 virtual machines then vms crashed and disk error occured, windows offered to automatically fix the problem then this problem occured

Any solution?
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Re: Differencing Image of Snapshot, Open Hard Disk Not Found

Postby mpack » 7. Jan 2014, 19:28

The possible solutions are given in my answer above.
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Re: Differencing Image of Snapshot, Open Hard Disk Not Found

Postby haytham.med » 7. Jan 2014, 19:44

the scan drive test said deleted files are in "found" folder, but i don't know where that is

What is meant by base vdi?

And how to avoid this error in future?

Should i not use snapshots?

and thanks
Last edited by haytham.med on 7. Jan 2014, 19:48, edited 1 time in total.
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Re: Differencing Image of Snapshot, Open Hard Disk Not Found

Postby mpack » 7. Jan 2014, 19:47

The base VDI is the original VDI created/referenced when the VM was created. The first snapshot is a delta depending on the base. The second snapshot is a delta depending on the first snapshot and hence also the base. And so on. Snapshots are linked using UUIDs. One of your UUID-identified files is missing.

Nobody in their right mind uses snapshots. The description I just gave should make it obvious why not!
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Re: Differencing Image of Snapshot, Open Hard Disk Not Found

Postby ChipMcK » 8. Jan 2014, 13:12

haytham.med wrote:What is meant by base vdi?


When a virtual disk is first created for a new virtual machine, it is considered as the base disk for the guest - data for the guest is read from and written to that disk image.

The differencing disk records changes sector-by-sector to the whole disk image, not changes to any file in the disk. VirtualBox does not know what file system is employed on the disk image and therefore can not access any individual file of/on the disk image; only the guest OS is aware of that information.

First SnapShot creates a differencing disk for read/write access while the base disk becomes read-only - as the guest modifies its data, the data is written to the differencing disk and the base disk is untouched.

Second SnapShot creates another, new, differencing disk for read/write access while the first differencing disk becomes read-only along with the base disk.

Subsequent SnapShots create additional differencing disks, with the preceding differencing disk joining the hierarchy (pecking order/chain) of read-only disks.

Keep in mind that access to/from the virtual disks is sector-by-sector, not file-by-file.

When the guest requests that a sector be read, the latest SnapShot is read first. If the sector is not found there (Sector-Not-Found is returned), the next SnapShot in the chain (youngest to oldest) is read, until the base virtual disk is reached. Then the sector on/in the base virtual disk is either read or Sector-Not-Found is returned.

Updated 2016-09-19 to fix partial sentence in last paragraph
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