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[NotSupported] VDI Disappeared: Recreate From SAV Snapshot?

PostPosted: 21. Aug 2019, 13:41
by MontyMan
I am experiencing disk errors on my host Linux Mint 19 system, and one day my VDI for my Windows 10 VM disappeared. I tried to start the VM and got a "file not found" error. However I have a 2019-07-24T09-48-32-208072000Z.sav file which is 968 MB approx the same size as the HDD was, and it's located in /home/monty/VirtualBox VMs/New Group/LatWin/Snapshots.

I plan on using fsck's to repair my Linux file system. Can the VDI be recreated from the snapshot file? Using version 5.2.18.

Best,
...Monty.
VirtualBox - Error
Failed to open a session for the virtual machine LatWin.

Details: Could not open the medium '/home/monty/DellW10withRecovery.vdi'.

FD: error VERR_FILE_NOT_FOUND opening image file '/home/monty/DellW10withRecovery.vdi'
(VERR_FILE_NOT_FOUND)

Result Code: NS_ERROR_FAILURE (0x80004005)
Component: MediumWrap
Interface: IMedium(4afe423b-43e0-e9d0-82e8-ceb307940dda)

(Copy) (OK)

Re: VDI Disappeared: Recreate From SAV Snapshot?

PostPosted: 21. Aug 2019, 14:49
by mpack
No, a VDI cannot be recreated from a snapshot file, and p.s. there is absolutely no way your Windows 10 VDI was ever around 1GB. It takes about 20GB to install Windows 10 Pro 64bit.

Incidentally, a SAV file is a saved state file, which is not what people consider to be a snapshot file (regardless of the name of the folder where you found it). A SAV contains the contents of RAM, not the contents of any disk. Snapshots have the VDI extension.

I'm afraid that if the base VDI file is truly gone then the only possible recovery is from your last VM folder backup.

I find it shocking that files can simply disappear from a Linux filesystem, regardless of the event or the error. On Windows hosts a similar occasional event might corrupt the first cluster (4k) of a VDI file, but the VDI is almost always repairable after that. I'd say that the primary responsibility of any OS is to protect user data. There should be no circumstance short of total drive failure which should cause the loss of 100s of MB (or GB) of data in a single event.

Re: VDI Disappeared: Recreate From SAV Snapshot?

PostPosted: 21. Aug 2019, 16:02
by MontyMan
Dear MPack,

You are correct; that amount of data is in no way comparable to my Windows 10 system disk size. I got my gigs and megs mixed-up; thanks for that.

I concur with your finding on the backup; in my case that was six months ago when I converted the VHDX to VDI; I still have the files from that and I will work on re-converting the VDI to support the VM, as soon as I've fsck'd to repair my file system (and if that fails, re-install Linux).

Yes I was very unpleasantly surprised to see the VDI gone; I had experienced a disk-full error when trying to copy an unrelated (but obviously large) file into the Linux file system. Several days of heavy disk usage went by before I tried the Windows 10 VM again (I normally use Windows about once a week) so I didn't even try undelete tools.

I did very little as far as changes to the Windows 10 VM in those months, and some upcoming weekend when I can make some time I'll recreate it.

Thanks much, ...Monty.

Re: [NotSupported] VDI Disappeared: Recreate From SAV Snapshot?

PostPosted: 27. Aug 2019, 14:32
by MontyMan
Final chapter is that I re-converted the VHDX files from December into the VDI, got the VM working and went through all the Windows Updates. And made a backup of the resulting VDI to removable media this time! Now the VM is ready to activate, change the installed software as I wish, and continue the process of verifying all data and memorized passwords have been backed up and/or moved into the host system.

I booted into a Linux live environment and fsck could find nothing wrong with the file system; I still have no idea what caused the VDI I was using to disappear.

Make backups, folks! And a snapshot isn't a backup.

Thanks and best regards,
..Monty.

Re: [NotSupported] VDI Disappeared: Recreate From SAV Snapshot?

PostPosted: 27. Aug 2019, 17:28
by socratis
MontyMan wrote:Make backups, folks! And a snapshot isn't a backup.

Amen to that, both statements!!!