calculate required temp storage and check available storage before merging snapshots

[treaki]

Hi there,

snapshots are a grate tool for tracking down changes and secure rolling them back. But they can become very memory consuming. If you run out off disk memory while your vm is running that isn't a big problem. The vm is getting paused and you can free up some memory and resume it afterwards without problems. But if want to free up some disk space you would probably just like to get rid of some old snapshots. But while doing that the merge process will take up first much more temp memory while doing that. The problem is if you run out of memory then you'll get a much bigger problem because it will brake your whole configuration and you have to manually do changes in the xml styled .vbox file to fix them up again.

So could you please calculate the maximum temp space which could be needed to merge snapshots and asking the user if they really want to do it before starting if there isn't enough space left.

And if you run out of space while merging/deleting snapshots please do something that wouldn't crash the whole process with an unusable vm afterwards but maybe pause the process until the user freed up enough space and/or rollback to the last stable state on auto.

It would be also nice to have a feature to delete more then one snapshot at once (while efferently doing that, so dont waste resources while merging with another snapshot that is going to be deleted anyways)

Thanks in advance