vdi disk got filled up and now VirtualBox refuses to revert to an earlier snapshot

[dndrdm]

Hello,

I am running VritualBox 5.2.18, host OS being Ubuntu 18.04 and guest being Mint 19.

In Mint I have a riscv/rocket-chip environment setup in order to simulate behavior of a processor and observe its output waveforms, given the input in the form of c/assembly programs. Once I had installed the Mint OS I created a snapshot, and then again, once I had setup the environment, I created another snapshot and only then moved on to run different simulations.

The output waveform files do tend to get big, so my VDI is 110 GB fixed-size. Nevertheless, yesterday the simulation went on and on, and the output waveform file simply filled the whole VDI, completely.

That I conclude from this is the message I get when I try turning the VM in its current state:

An error has occurred during virtual machine execution! The error details are shown below. You may try to correct the error and resume the virtual machine execution.

The I/O cache encountered an error while updating data in medium "ahci-0-0" (rc=VERR_DISK_FULL). Make sure there is enough free space on the disk and that the disk is working properly. Operation can be resumed afterwards.

Error ID: BLKCACHE_IOERR
Severity: Non-Fatal Error

So, ok - it makes sense: the file got to big, filled up the disk, the VM can't boot. Ok, no problem there. However, once I tried bringing back the snapshot (either one of them), I get:

Failed to restore the snapshot intenuser of the virtual machine rockettest.

Result Code: VBOX_E_FILE_ERROR (0x80BB0004)

And this, definitely, is not ok - it brings me into a terrible position, as it completely destroys the work on setting up everything.

I tried increasing size of the VDI, but for some reason - I am not allowed to type in the new size (image attached - 1).

VirtualBox does allow me to enter the new size for a snapshot (image attached - 2), but once I click Apply, that leads to a new error:

Failed to resize the storage unit of the hard disk /media/aleksandar/Elements/VirtualMachines/rockettest/Snapshots/{814f10d6-c461-4860-be1c-4da0540701b3}.vdi from 100.00 GB to 120.00 GB.

Could not resize medium '/media/aleksandar/Elements/VirtualMachines/rockettest/Snapshots/{814f10d6-c461-4860-be1c-4da0540701b3}.vdi' (VERR_DISK_FULL).

Result Code: VBOX_E_FILE_ERROR (0x80BB0004)
Component: MediumWrap
Interface: IMedium {4afe423b-43e0-e9d0-82e8-ceb307940dda}

Please help.

[dndrdm]

unable to type in the new size of vdi when trying to resize it

[dndrdm]

able to type in the new size when trying to resize the disk of a snapshot, but unable to apply it later on

[Socratis]

1. It's usually better and faster, if issues get first addressed in the ​VirtualBox forums, a lot more eyes there. More than 95% of the issues are resolved in the forums, which keeps the developers focusing on the bug fixes and enhancements, and there is no need for another ticket to keep track of. For example, yours is most probably not a bug and someone from the developers has to deal with it and close it as "Invalid".

Plus a discussion and analysis on the bug tracker is going to help me, you, and potentially a future drive-by user or two. Not so in the forums, many more tend to benefit...

2. The "VERR_DISK_FULL" error doesn't refer to your VDI being full, but your host's "/media/aleksandar/Elements" being full. You need to free some space on that Elements drive, it can't afford the 200 GB that you're asking it for (100 GB for the fixed VDI + up to 100 GB for the snapshot).

3. Of course you can't resize a fixed VDI. From the User Manual:

   This option [sic: resizing] currently works only for VDI and VHD formats, and only for the dynamically allocated variants. It can only be used to expand, but not shrink, the capacity.

I believe that this ticket can be closed as [Invalid].

[dndrdm]

Hi socratis,

thanks for the comments, answers embedded below.

Replying to socratis:

1. It's usually better and faster, if issues get first addressed in the ​VirtualBox forums, a lot more eyes there. More than 95% of the issues are resolved in the forums, which keeps the developers focusing on the bug fixes and enhancements, and there is no need for another ticket to keep track of. For example, yours is most probably not a bug and someone from the developers has to deal with it and close it as "Invalid".

Plus a discussion and analysis on the bug tracker is going to help me, you, and potentially a future drive-by user or two. Not so in the forums, many more tend to benefit...

Thanks for the tip, I just felt that this behavior is at the level of a bug - hence I wrote here. Another argument in that direction in response to the second comment, below.

2. The "VERR_DISK_FULL" error doesn't refer to your VDI being full, but your host's "/media/aleksandar/Elements" being full. You need to free some space on that Elements drive, it can't afford the 200 GB that you're asking it for (100 GB for the fixed VDI + up to 100 GB for the snapshot).

Fortunately enough, one of the earlier snapshots I exported as an appliance. Once I imported that back in (also stored in Elements), I could boot that imported machine. So, if VirtualBox boots that (and I just tried, others VMs as well - which are also ~100 GB in vdi size), why can't I boot nor revert a snapshot of the VM that got filled up by my simulation?

3. Of course you can't resize a fixed VDI. From the User Manual:

   This option [sic: resizing] currently works only for VDI and VHD formats, and only for the dynamically allocated variants. It can only be used to expand, but not shrink, the capacity.

I believe that this ticket can be closed as [Invalid].

Thanks for pointing that out - I should've paid more attention to the doc, I apologize.

[Socratis]

Replying to dndrdm:

Fortunately enough, one of the earlier snapshots I exported as an appliance. Once I imported that back in (also stored in Elements), I could boot that imported machine. So, if VirtualBox boots that (and I just tried, others VMs as well - which are also ~100 GB in vdi size), why can't I boot nor revert a snapshot of the VM that got filled up by my simulation?

Because your guest OS is most probably in a state that it can't recover. Because it run out of space while in the middle of writing. Something catastrophic happened (no more space) and it can't recover from it. It happens with real systems too. It happened to me many years ago actually on an WinNT4 workstation. Couldn't boot because it was full.

And the 100 GB VDI size is definitely not relevant here. The fact that your host has a problem, is. And the only solution is to free up to 200 GB of space from your Elements so that you can revert your snapshot. Reverting a snapshot also requires HD space, possibly as much as the VDI+snapshot, but usually less.

And that's why I said to open a new thread in the forums:

1. A consensus could be formed on why exactly things are happening. Right now I'm 90% sure that this is what's happening, so, a second opinion wouldn't hurt, au contraire, it would definitely help.

2. The rest of the users would benefit; not a lot of users lurk in the bugtracker.

3. You still can open a thread and cite the ticket. ;)