[WorksForMe] Year-old snapshot booting after resizing virtual machine

[irodg92]

When I resized the VDI (Ian Windows 10 NEW) following the instructions on the video (removing the attachment-the VDI-and adding it back after resizing it), it booted up from a snapshot taken on 2/26/17 instead of booting from the state of the machine on 4/20/18.
1. I'm assuming that information is not recoverable if I don't have the data backed up, but want to confirm.
2. Assuming 1 is true, I have a backup of my MacOS that includes a copy of the VDI from the end of January 2018-if I create a new machine from this backed up VDI, will it still only boot from the Feb. 2017 snapshot or is there a way to boot it from the day of the backup?

[socratis]

You have the following snapshots:

• "Snapshot 1" timeStamp="2017-02-26T17:17:42Z" stateFile="Snapshots/2017-02-26T17-17-42-918014000Z.sav
• "Snapshot 2" timeStamp="2018-04-21T22:56:32Z" stateFile="Snapshots/2018-04-21T22-56-32-640822000Z.sav
• "Snapshot 3" timeStamp="2018-04-22T15:19:35Z"

So, you have 3 snapshots, 2 of which were taken while the VM was running (tsk, tsk, tsk). The current VM state is:

name="Ian Windows 10" OSType="Windows10_64" currentSnapshot="{98105a2c-3b4d-4adf-b123-b25fcaf6c614}"

which corresponds to "Snapshot 2":

<Snapshot uuid="{98105a2c-3b4d-4adf-b123-b25fcaf6c614}" name="Snapshot 2" timeStamp="2018-04-21T22:56:32Z" stateFile="Snapshots/2018-04-21T22-56-32-640822000Z.sav">

So, what if you switch to the "Snapshots" tab in the VirtualBox Manager, select "Snapshot 3" and click on "Restore"? That should take you to the snapshot from 2018-04-22T15:19:35Z.

Next step will be to merge these snapshots and do a proper resize, like nature intended. But, switch to that snapshot (Snapshot 3) first.

[mpack]

I have a backup of my MacOS that includes a copy of the VDI from the end of January 2018-if I create a new machine from this backed up VDI, will it still only boot from the Feb. 2017 snapshot or is there a way to boot it from the day of the backup?

You need to understand how snapshots work.

In the beginning was your base disk, you probably installed the OS into that. Life was simple, hard to mess up.

At some point you decided to create a snapshot. The base disk contents was frozen and a new "difference image" is created (vdi with funny name in snapshots folder). The difference image records only the sectors which have changed since the snapshot was created. So, every time an app writes to the disk, the VM either adds a new "sector changed" record to the difference image, or it updates the record which already exists (if you wrote to that sector before). When reading from the disk the VM first looks to see if the target sector is contained in the difference image, if not it gets read from the base disk.

At some point you decided to create a second snapshot. This works exactly the same as before, except replace the term "base disk" with "previous difference image". Now when reading from the disk the VM first looks to see if the target sector is contained in snapshot 2, if not there it looks in snapshot 1, and if not there it reads it from the base disk.


Now. The main point to note is that the base disk never changes after the first snapshot is created. So if you have a VM backup taken after the first snapshot was created then the base VDI in that backup will be perfect for restoring the damaged base VDI in the latest VM.

But, it isn't only the VDI files that need to be restored. A snapshot chain is heavily dependant on the control information about the chain which is stored in the .vbox file. So ideally you need to restore the .vbox file to its pre-Youtube state as well. If you can't do that then let us know: in that case we'd have to perform emergency procedures that will recover your data (provided you have a complete VDI chain), but it may cause you to lose activation of Windows and other software inside the guest.

[socratis]

mpack, I actually imported the .vbox in my VirtualBox Manager to study it. This is the current state of affairs:

↓ Snapshot 1                        2017-02-26 19:17
    ↓ Snapshot 2                    2018-04-22 01:56
          Snapshot 3                2018-04-22 18:19
          Current state (changed)

If you notice, the "Current state" is at the same level as "Snapshot 3", which means that the "Current state" is actually a child of "Snapshot 2" (that's why "Snapshot 2" is bold).

So, my impression is that 'irodg92' needs to select "Snapshot 3" and then hit the "Restore" button. That should bring order to the universe, before we start hacking it any further...

[mpack]

If the base VDI and the .vbox file can both be restored then it should produce a working VM.

In that case I would immediately clone the VM (current state only, don't reset MAC). That should give a new VM with a merged VDI which can easily be resized per the FAQ (i.e. resize disk then update the partitions).

[socratis]

That's my gut feeling as well, that the whole thing is working right-out-of-the-box. It was simply a matter of selecting an older VM state... Only if selecting "Snapshot 3" is successful, then

Next step will be to merge these snapshots and do a proper resize, like nature intended. But, switch to that snapshot (Snapshot 3) first.

I'd suggest using your Cloning idea (for safety), but I would personally choose to slowly merge the snapshots back to a single VM state.

[irodg92]

Socratis, I created Snapshot 2 and 3 after I had the problem-I saw that my VDI's "last modified" date in my Finder was before I originally messed everything up, so I took a snapshot of it then. Unfortunately once I opened it with snapshot 3, it turned out to just be a snapshot of the 2/26/17 snapshot (Snapshot 1). I'm assuming this means I'm out of luck, as restoring Snapshot 3 is basically just restoring Snapshot 1?

[socratis]

Yes, if you took the snapshots after you messed up your setup, you're out of luck I'm afraid.

[irodg92]

Okay. Thank you very much for all your help, I really appreciate it.

[socratis]

Sorry we couldn't help, but we can't be inventing things... At least a couple of things came out of this; 1) you value the concept of a good backup, and 2) now you know where to turn for advice/help before you attempt to do something.

Marking as [WorksForMe].

[mpack]

Do you or do you not have available all of the original VDI files from the pre YouTube VM? If yes then the situation is recoverable as I said above, though you may have to reactivate Windows and potentially any other guest software which relies on activation.