Snapshoot Image IDs

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Snapshoot Image IDs

Postby iwl » 17. Apr 2021, 12:02

Hi group,

when I delete a snapshoot with childs the image of the deleted snapshoot is merged into the child images and deleted.
So the images of the childs are changed but the imagenames/ids seem to stay the same, which has some logic representing the same state.
The only problem is I backup my virtual machines, .vbox file with git and the images as files.
So after merging I may have different Image-Files with same name.
The newest may be fine, but dates sometimes change copying around.
Usually the last one should be the biggest, but I'm not sure.

May be there are some more ideas about the topic...
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Re: Snapshoot Image IDs

Postby scottgus1 » 17. Apr 2021, 14:55

If the snapshot delete process completes correctly (*) the .vbox file will contain the correct pointers to the existing condensed snapshot chain. Thus the .vbox file goes with that new snapshot chain and cannot be used with a different snapshot chain. The same consideration goes for the VM's hardware recipe, which also can change with different snapshots: the wrong .vbox file will present the wrong hardware, causing confusion in the VM's OS.

You report backing up the .vbox file with git and the disk files as files. This setup is apparently de-synchronizing the .vbox from the snapshot chain. You need to back up the .vbox and the snapshot chain together as one backup unit. The .vbox file going with the snapshot chain should be backed up with the chain files as another file in the backup, not on a separate path that could and apparently does put the wrong .vbox and chain together.

The best restorable backup of a VM is to copy the whole VM folder, with .vbox and all disk files, while the VM is shut down not save-stated, to other media. Then the backup can be fc-file-compared to confirm backup integrity.

* Snapshot deletion sometimes fails, leaving a dead VM. A restorable backup of the VM before deleting snapshots is a good ides.
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