Q&A on Microsoft Virtualization, Part 2

Ben Armstrong discusses app compatibility and enterprise Azure development.

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We continue our interview with Ben Armstrong, Microsoft's program lead for Hyper-V. You can find Part 1 here.

Paul Schnackenburg: How much of the direction of your engineering work is now influenced by Azure, compared to what enterprises asks for?

Ben Armstrong: So before we even released the first version of Hyper-V, we had an engineering team working on Azure. What was actually happening at that stage was we had the team working on Hyper-V for enterprises, and we had the team working on Hyper-V for Azure where every six to nine months we were doing code exchanges back and forth, and comparing notes and syncing up.

Windows Server 2012 was a big moment for the team in many fronts, but one of them was that it was the first time that we got those code bases back together. From Windows Server 2012 onwards the Hyper-V that you have on your server, the Hyper-V that you have on your laptop, is the same Hyper-V that we run in Azure.

Now from the Hyper-V team perspective when we're working on a release we have a lot of customers that we consider. The Windows Server and the enterprise environment is definitely one of those customers; so is Azure, so is Windows Client.

I don't know how familiar you are with the Credential Guard feature, but that's amazing stuff that we did for Windows Client and Windows Server ... and Server 2016 is no different; in every release there's 10 times more that we want to do than we actually do, and we basically go through and know we have to do the mental math of "OK, who's asking for what, what's the prioritisation, what's the business impact?" So I wouldn't say we rate one more over the other. We just look at what's going on and where the need is.

PS: Obviously. The use case for Hyper-V in Windows 10 and Client -- way back there was XP mode and it was a bit of an application compatibility thing. If you were running 7, you could run your app in XP, but do you see that as the use case nowadays?

BA: Absolutely not. Let me give a bit of a detail on this. This is a hotly debated topic inside Microsoft and it's one of the things that I love about Microsoft and our approach to client virtualization. Whenever we look at using virtual machines on the desktop to solve a problem, one of the first questions that we ask is, Could we solve this better by just fixing Windows?

And that's kind of our position: we should never use virtualization on the desktop as a Band Aid. Like good engineers we should always be focussed on what's the best way to solve this, and if the best way to solve this is by fixing Windows, then let's go fix Windows.

And so in that kind of vein, there's always been a huge argument about what role virtualization can play for application compatibility on the desktop, because it is very much an area where you can make a strong argument for … just running on Windows. We do have a substantial app compatibility team inside Windows that's responsible for going through testing and validating.

So when we released Windows 7, we knew we had a lot of customers who had applications that wouldn't run. We had that data from Vista and we made the investment in doing the Windows XP mode to address that pain point. Where we're at today … the app compatibility pain point for Windows 10 is actually a lot lower than it was for Windows 7. Yes, there are still some apps out there that don't run, but we've been focusing on app compat and the platform ... I don't know the exact number, but the vast majority of apps that run on Windows 7 run on Windows 10. So we don't see a huge demand for that.

Where we've actually been focusing the majority of our time on Hyper-V for desktop has actually been in two areas. The first one is actually all the security work that we've been doing, so Credential Guard, Device Guard, some really cool virtualization security. Tipping my hat a little, but without tipping it too much, that's an area we're going to be investing in more going forward. There are more scenarios and more situations that we've been able to think of where we're like, "Hey, we can up the bar here."

About the Author

Paul Schnackenburg has been working in IT for nearly 30 years and has been teaching for over 20 years. He runs Expert IT Solutions, an IT consultancy in Australia. Paul focuses on cloud technologies such as Azure and Microsoft 365 and how to secure IT, whether in the cloud or on-premises. He's a frequent speaker at conferences and writes for several sites, including Find him at @paulschnack on Twitter or on his blog at


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