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I have a Virtualbox virtual machine that I use on an almost daily basis. When I exit I usually save the state of the machine, but all important data has been saved.

On the same machine I run Backblaze (one of those remote backup solutions), and I recently noticed that it's often trying to backup huge .sav files, thus affecting my network connection.

My understanding is that that file contains the currently saved state of the Virtual Machine. Do I really need to backup it? What would happen if I were to recovery the hard disk state without the .sav file? Wouldn't that just show me the Virtual Machine as it was the last time that I rebooted it?

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up vote 4 down vote accepted

The .sav files are created when you suspend your VM.

enter image description here

VBoxManage adoptstate

If you have a saved state file (.sav) that is seperate from the VM configuration, you can use this command to "adopt" the file. This will change the VM to saved state and when you start it, VirtualBox will attempt to restore it from the saved state file you indicated. This command should only be used in special setups.

So as long as you are saving unsaved things to the to VM's disk drive before you suspend then there is not much of a need to back up those files. So if your VM can afford to be forced off with out saving changes then you don't need the .sav files, otherwise you might want to keep them. But yes it will be just the way the machine was the last time it was booted, kind of like a Real PC that suffered a power failure.

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I'd give it the good ol' fashioned test by performing a mock recovery on another machine without those .sav files and see if your virtual machine lost any important data.

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