virtualbox.org

I am usually taking a snapshot of a VM before upgrading VBox to a new release. When the new release works reliable I take another snapshot ... and so on. This results in a chain of snapshots. Currently I am on VBox 4.1.4.

I would now like to know whether it is safely possible to delete i.e. the very firs snapshot of such a chain without any impact on the functuonalit of the subsequent snapshots. This is nowhere in the manual stated explicitely, it only talks about "general deleting = merging snapshots". BTW: it actually would be more accurate to name that action merging instead of deleting.

With best regards,
Ingo

Snapshots are not backups for host activities. If you want the ability to revert a VM along with a VirtualBox version then you should use backups, not snapshots.

Thanks for your reply. If I understand your answer well, that means one must not preserve snapshots if they are created with different VBox-versions? It also means that before upgrade one should merge/delete all snapshots and shutdown the VM, so there only renmains a single *.vdi file?

But what about if snapshots are created all with the same VBox-version:
> I would now like to know whether it is safely possible to delete i.e. the very first snapshot of such a chain without any impact on the functuonality of the subsequent snapshots.

Best regards,
Ingo

Frankly, I do not use snapshots at all - they can be broken by too many things. One thing that has certainly been known to break them is a bug introduced by a new VirtualBox version. Often by the time the problem is discovered the damage is already done and there is nothing you can do to recover - unless you have a backup. Note however that this is simply one example: snapshot structures are fragile and lots of things break them.

Basically, backups always do the same job: in case of any disaster, the backup is available to limit your losses. But in the VirtualBox context, in case of a disaster scenario, snapshots are the very first things that stop working. Hence their utility as a backup medium is close to zero.

Which is why I say that snapshots should not be confused with backups. At best a snapshot provides a quick way to roll back changes inside the guest. They do nothing for problems with the host.

Many thanks for your straightforward answer. That was also my suspicion (snapshot feature not guaranteed reliable) and is the reason why I made this posting (manal also does not give clear statements on this matter).

I do know that snapshots may not be considered backups, so the most feasible solution would be to take a confirmed good *.vdi image and attach it as 'immutable' so it will never be written to. Till now I never observed that VBox altered an immutable image (verify by md5sum). With a secure backup of this *.vdi , this saves you a lot of data to be transferred/backup'd every time, because all write operations in such a VM go to the differencing image.

Best regards,
Ingo

And its not only a VBOX problem. In VMWARE Forums this a problem too.

I only use one vdi file. On vmware one vmdk, not splitted. No clone, no snapshots. => No problem.

I have a big USB3 hd for backups and sometime after system updates or something else i copy the vdi file to the backup disk.

And if i test something, i first backup the vdi, then install software in the guest. And if there a problems, delete test vdi and copy back old one.

This needs more time for such operations, but save many times if there else will be problems.

I really appreciate your valuable answers and recommendations.

Till today I always asumed that the vdi-format is well fixed and tested. The snapshot mechanism probably changes from time to time to adopt new features, but as VBox is also used in commercial environment, so vdi-integrity was never a consideration for me.

I only was wondering how little information on managing snapshots you find in the manual and therefore asked the question here before firmly relying on snapshots. I do not blame VBox for any snapshot problems in general, but it would be helpful if such issues were explicitely mentioned in the manual. Or even better: if extensive tested and prooven good and reliable releases would be marked as such and maintained separately from development branch.

With best regards,
Ingo

Hmm. I can't think of any software products that highlight their own design weaknesses in the user manual or promo material! That's what user forums are for...

VMWare has snapshots, so anyone trying to compete with VMWare has to implement them. Users love them. That does not mean they are a good idea. I don't use snapshots either, in VirtualBox, VPC or Hyper-V. I don't use VMWare.

I created several snapshots in the early going thinking they were like backups. Now I'm realizing they are not really reliable in this manner and.. they are taking up way too much hard disk space. I want to be sure that the current state of each VM is being safely saved each time I shut down a VM properly. Knowing this would give me great peace of mind.

On my Windows 7 VM I have only one remaining snapshot but when trying to delete it, I get the message that it can't be deleted because it has more than one child. In actuality, it has no children whatsoever. How can I delete this last snapshot?