virtualbox.org

If you wanted to use to install Oracle VM on an external drive an operating system like I do? Let me explain: I have to install Ubuntu on an external drive and then use it on another computer. Having no other PC available I wanted to use VM to physically install the operating system in order to continue working pda. This is possible?

Oracle VM is not supported on this site, only VirtualBox is supported here, which is an entirely different product. Confusingly, when Oracle bought Sun the name did change to "Oracle VM VirtualBox" to make people think there was a grand plan.

If we restrict the discussion to VirtualBox then yes, you could map the external drive as a raw disk and then install the OS. Of course the OS will be using drivers for virtual hardware (even the "raw drive" is a virtual device which just happens to be mapped sector for sector to a physical drive surface), so getting the same OS to run on physical hardware could still be an unheaval. If it was a recent Windows it probably wouldn't be worth it, Linux may tolerate the hardware changes better.