Updated: January 25, 2020
When it comes to virtualization - mostly semi-pro or casual usage you'd find in a typical nerd setting, VirtualBox offers an excellent bundle of goodies; a friendly UI, lots of features, reasonable performance, simple and advanced options to suit every skill and mood. I've written about VirtualBox many times in the past, reviewing a whole range of topics, from the Guest Additions configuration to sharing & port-forwarding and then some. Several dozen articles to be more precise. Including major release reviews among them, of course.
Recently, VirtualBox 6.X has been released, so I thought this would be a good opportunity to take a look at what's new, check some of the improvements and fixes, and see whether you should move off the 5.X branch onto the latest edition. Come along, let's see what gives.
Upgrade & first-steps
I've done the testing on my Slimbook Pro2 laptop, meaning Kubuntu 18.04 system. In Linux, there are two ways you can use this product. Through standard repos, where you get the free components only. Or you can use the full, unrestricted version by adding the VirtualBox repository to your system. This also gives you access to the VirtualBox extensions, meaning USB-2.0/3.0 connectivity and such. Then, if you already have the sources configured, VirtualBox 6.0/6.1 comes as a separate installation to the 5.X version. Indeed, the older edition still supports 32-bit hosts, whereas the new one is 64-bit only - you can still run 32-bit guests, of course.
I upgraded my system without any trouble, and also updated the extension pack. No issues. My virtual machines were retained, and all their settings correctly preserved, including snapshots. I did not encounter any bugs or such.
3D acceleration changes
However, I did see a warning regarding 3D acceleration with one of my VMs when testing version 6.0, mentioning that VboxVGA graphics control support feature will be removed at some point in the future, i.e. the next minor release. In layman terms, I do not know what this means - as in, I'm not sure what the results will be when it comes to performance and supported usage. I guess 3D acceleration will still be available, and all it takes is a configuration change & Guest Additions update in the worst case.
Nested hardware acceleration
I think one of the more interesting options is the ability to use nested virtualization. This means you'll be able to expose virtualization features of the CPU (the whole VT-x thingie) to virtual machines, and possibly create a setup with hardware-enabled virtualization that is several levels deep. One step closer to the Matrix.
However, at the moment, this only seems to work with AMD processors, and since my Slimbook uses Intel, this wasn't available, and the feature was grayed out. You can still toggle it in the terminal using the VirtualBox command line, but while the option then shows in the system settings, it won't actuall do much at this point. You can do this as follows:
vboxmanage modifyvm "virtual machine name" --nested-hw-virt on
Snapshots, paravirtualization, other settings
I played with a bunch of other options and settings, just to see what gives. You have a flexible and robust snapshot functionality, which is quite handy for testing multiple branches slash scenarios of your software setup. Do remember that you will have to handle snapshots separately if you intend to resize your virtual machine harddisks. Then, you can also change the paravirtualization interface - VirtualBox supports quite a few, in case your guest operating system requires special behavior. Tons of familiar tweaks, plus a powerful command line for the extra nerdy stuff.
There's nothing too revolutionary about VirtualBox 6.X, and yet, it feels like a solid, packed release full of goodies. Indeed, with every new edition, this product always gains some extra cool features, making it even more useful and practical than before. Considering the fact you can have it for free in the home setup, plus the versatile user interface, and it's definitely a go-to power tool for the advanced users and software testers.
You retain the old behavior and options, so there's no stress or drama. You also gain some, and I believe Intel processor users will also soon benefit from nested hardware acceleration, which will make things even more interesting - looking at VirtualBox 6.1 on the Slimbook, still not the case at the moment. All in all, the VirtualBox 6 release is the familiar workhorse with a few extra tricks. Quite recommended.