Hanging while deleting snapshot

[buckybob]

I am currently using an older version of VirtualBox (6.1.18) with a Windows 10 host and a Windows 10 guest.

While I was using the guest OS, I got a VERR_DISK_FULL error. VirtualBox is the main thing taking up space on my PC, so in order to fix this, I went to try to delete the latest snapshot for this guest OS. After some waiting, it gave me an error saying that I didn't have enough free space to do that. After that, I cleaned up what little space I could and made about 5 GB of free space. I then proceeded to try to delete the snapshot again. This time, the merging window started to hang. I decided to go to sleep and check back the next morning only to find that it had made no progress. Here is what I see:

virtualbox.png (49.89 KiB) Viewed 2806 times

When I hover over the merging window, my cursor changes to a spinning blue circle indicating that it's busy. It won't let me click on either the X in the window or the X in the upper right hand corner of the window in order to stop the process. When I try to click on the VirtualBox manager itself, the merging window flashes and it won't let me interact with anything.

What would be the next best step for me to take here?

(I noticed that viewtopic.php?f=6&t=62491&p=292258&hili ... ng#p292258 seemed to have a similar issue as to mine, but in my case, I am unable to even stop the process without end tasking VirtualBox, and I'm concerned that doing so may lead to further issues)

[mpack]

In order to delete a snapshot VirtualBox has to merge the changes back into the previous state, meaning it has to create a new VDI file to hold the data from two of the existing states - and when that succeeds it can fix up the UUID links and delete the old file.

I.e. it needs space to work. I'm sure you can find stuff to offload from your primary drive even if temporarily.

At this point I rather suspect it may be too late for you. You can leave it a bit longer or kill the task in Task Manager. If you're lucky you'll be back to where you were. No choice now.

I recommend that you stop using snapshots, that way the space they take up can never be an issue, and nor can you ever suffer the otherwise inevitable snapshot-related catastrophe. Use offline backups when you want to preserve a VM state.

[buckybob]

Thanks for the quick reply. Fortunately, end tasking VirtualBox seemed to work and I was able to restart the VM without issues.

Also, thanks for the recommendation. I've been using snapshots as a sort of backup in case something happens, but if these kinds of issues can happen, it definitely sounds better to make an offline backup.

[scottgus1]

Snapshots definitely are not backups. They're more like time-travel and parallel-universe markers in the VM's lifetime.

Any backup routine that contains taking a snapshot is not good. If you want to discuss the concept, please start a new topic.

Mpack's offline backups concept is the best way to back up a VM: while the VM is completely shut down from within the VM's OS, copy the whole VM folder, and any disk files placed outside the VM's folder.

Running backups of a live VM should be done with inside-the-VM-OS 3rd-party live backup software, saving to another host or network disk through a real non-Virtualbox-provided shared folder.