Error at the end of snapshot delete makes vm unusable

[dumischbaenger]

Hello,

I tried to delete a snapshot of one of my virtual machines. At the end of the merging process virtualbox came up with an error. Now I cant start my vm. The error message is:

could not open the medium '/local/aluht_rondell/Snapshots/{f5555998-9ca0-41a0-86bb-3ecaf9880dd2}.qcow'.

VD: error VERR_FILE_NOT_FOUND opening image file '/local/aluht_rondell/Snapshots/{f5555998-9ca0-41a0-86bb-3ecaf9880dd2}.qcow' (VERR_FILE_NOT_FOUND).

Fehlercode:NS_ERROR_FAILURE (0x80004005)
Komponente:MediumWrap
Interface:IMedium {4afe423b-43e0-e9d0-82e8-ceb307940dda}

And in fact .../Snapshots/{f5555998-9ca0-41a0-86bb-3ecaf9880dd2}.qcow is missing. VB was obviously able to delete it but somehow this disk image is still present in VB config files.

vbErr.png (55.34 KiB) Viewed 1168 times

Is there a chance to recover my vm?

Regards,
Bernhard

[mpack]

Nope. That's a dead VM, unless you can restore the lost file from a backup. Any backup taken after the creation of {f555.... can provide the missing file, since the contents were frozen at that point.

Failing that, the only data which can be recovered is the stuff in the base disk image, "aluht_rondell.qcow".

Incidentally, why "qcow" format?

[dumischbaenger]

Incidentally, why "qcow" format?

I don't know why. One of my colleagues created the vm. I guess he wanted to be "compatible" with KVM.

Two days ago I tried to export the vm but it was not possible. In the VB ticket system (#12626) was stated import (and presumably export) is not supported with qcow. Yesterday VB crashed while deleting a snapshot perhaps due to the use of qcow. Is qcow finally a valid alternative to the native VB disk format?

[mpack]

Is qcow finally a valid alternative to the native VB disk format?

I would not concede that there are any valid alternatives to VDI, the native VB disk format, if your goal is total compatibility with VirtualBox. However that is just a personal opinion.

The other formats are provided as a... well I guess as a convenience for people migrating from other VM platforms, but I don't really know. Personally I would always use VDI (plus I'd never use snapshots), and I'd use "VBoxManage clonemedium" to convert to other formats as and when the need ever arises.

I've never seen anyone using qcow in VirtualBox before, so even among the non native options, it's not a well proven choice.

[Perryg]

qcow is a file format for disk image files used by QEMU. Works well in that virtualizer but not so good in VirtualBox. That said it should basically work, but for my part I would not press the image hard. Basic configuration testing and not much more. I certainly would not use it for anything important and especially not use snapshots.