When Microsoft first announced Windows 10 build 10565 to Windows Insiders the other day, it neglected to mention a very interesting new feature that is debuting—in very early form—in this build. It’s called nested virtualization, and it appears to dramatically change how Hyper-V works.
That said, it’s not clear that this change will impact users on the Windows 10 client all that much. Instead, nested virtualization is really aimed at Windows Server 2016—the server-side sibling of Windows 10—where Microsoft is evolving the system’s virtualization platform to include support for containers. And among the promised capabilities in Windows Server 2016’s support for containers is the ability to run Hyper-V Containers inside of Hyper-V virtual machines.
What this means is that Windows 10 and Windows Server 2016 are being updated to support nested virtualization, or more specifically the ability to run Hyper-V inside of Hyper-V. And we’re seeing the first glimpse of this feature in Windows 10 build 10565. (Windows Server 2016 is on a much more measured release schedule and won’t ship in initial form until next year.)
If you have used Hyper-V in the past—or, have tried and failed to get Hyper-V installed—you may understand why this is a big deal: Hyper-V requires very specific hardware support, like Intel VT-x and AMD-V chipset capabilities, before you can even install this feature. And many people with otherwise modern and powerful PCs have discovered to their dismay that Hyper-V simply isn’t available.
According to Microsoft, nested virtualization exposes hardware virtualization support to guest virtual machines. This allows you to install Hyper-V in a guest virtual machine (under Hyper-V only), and then create more virtual machines “within” that underlying virtual machine.
As noted, this feature likely won’t impact normal users too much. But for developers and those who rely on virtual environments installed on laptops for training and speaking engagements, nested virtualization will change things in a very positive way. Eventually. As this first implementation is quite buggy, Microsoft says.
“There are plenty of known issues, and there is functionality which we still need to build,” Microsoft’s Sarah Cooley notes. “We wanted to share this feature with Insiders as soon as possible though, even if that meant things are still rough around the edges.”
Microsoft provides a lengthy list of known issues, as well as steps to enable nested virtualization in its post, Windows Insider Preview: Nested Virtualization.
And if you are a tech trainer or speaker, you’re going to need a bigger SSD. 🙂