Posey's Tips & Tricks
Windows 8: Hyper-V on the Desktop
Virtualization solutions in Windows 8 will help with the data size for mobile devices.
Over the last several months quite a few details about Windows 8 have been trickling out of Redmond. One such detail that hasn't received a lot of attention yet is that the Windows 8 client (as opposed to Windows 8 Server) will include Hyper-V.
On one hand, the idea of having Hyper-V at the desktop level is easily dismissible. After all, Microsoft's Virtual PC has been around for years, and including Hyper-V support on the desktop is just another way of running virtual computers on a desktop operating system. Am I right? Maybe not.
I tend to think that there is a lot more going on than meets the eye. A few years ago, Microsoft was facing several dilemmas as they prepared to release Windows 7. Most of their customers were still using Windows XP, and the few that had upgraded to Windows Vista were extremely upset by all of the compatibility problems that they encountered when running legacy applications.
Microsoft came up with a rather unique solution to these challenges. The solution was to include a Windows XP license with Windows 7, and allow Windows XP to be run within a virtual PC. What made this solution so innovative was that applications installed on Windows XP were accessible through the Windows 7 desktop, which freed users from the burden of switching back and forth between desktops. In fact, users may not even realize that some of their applications were actually running on Windows XP.
There are still a lot of details about Windows 8 that have yet to be revealed, but it seems completely plausible that Microsoft could take a similar approach to providing backward compatibility in Windows 8. However, I actually expect to see them take things a few steps further.
Microsoft has said from the beginning that Windows 8 will be able to run on desktop CPUs, but that there will also be an ARM version that is designed to run on mobile phones and tablets. The idea is to give users the same operating system experience regardless of which type of device they are using.
While this is certainly a good idea, some have wondered why Microsoft didn't take this approach with Windows 7. After all, the Windows 7 and the Windows Phone 7 operating systems are very different from each other.
I think that one of the big reasons why Microsoft didn't attempt to shoehorn Windows 7 onto their latest Windows Mobile devices is because the operating system is simply too large. According to Microsoft  Windows 7 requires 16 GB of available hard disk space. By way of comparison, the total amount of storage space on my Windows Phone 7 device is 16 GB. As such, it might theoretically have been possible to cram Windows 7 onto such a device, but there wouldn't have been any resources left for installing or running apps.
In order for Windows 8 to run on a mobile device then the operating system would need to be much smaller than Windows 7. One of the most effective techniques that Microsoft could use for slimming down the operating system would be to get rid of all of the code that is designed to provide backward compatibility. Doing so would result in a much smaller, more efficient and arguably more stable operating system.
Of course Microsoft can't just get rid of all the backward compatibility features if they expect anyone to upgrade from a previous version of Windows. That being the case, I expect to see backward compatibility implemented solely through virtualization. Whether Microsoft will use application virtualization or operating system virtualization remains to be seen, but I do expect virtualization to play a major role in Windows 8.
Using this approach would keep the core Windows 8 operating small and fast, which is perfect for use with mobile devices. Hyper-V could be used to add the required backward compatibility, but without bogging down the main operating system. My guess is that Microsoft will let you pick and choose which operating systems you need to provide backward compatibility with. That way, you won't have to waste resources (or open security holes) by installing code for operating systems that are not needed. This is the same basic approach that Microsoft currently takes with Windows 7. Those who need Windows XP support can install Windows XP mode, but it isn't installed by default and running it certainly is not a requirement.
For right now, all we can really do is speculate on Windows 8 based on the information that has been leaked from Redmond. We won't have a clear picture of Microsoft's approach until the first public beta has been released.
About the Author
Brien Posey is a 22-time Microsoft MVP with decades of IT experience. As a freelance writer, Posey has written thousands of articles and contributed to several dozen books on a wide variety of IT topics. Prior to going freelance, Posey was a CIO for a national chain of hospitals and health care facilities. He has also served as a network administrator for some of the country's largest insurance companies and for the Department of Defense at Fort Knox. In addition to his continued work in IT, Posey has spent the last several years actively training as a commercial scientist-astronaut candidate in preparation to fly on a mission to study polar mesospheric clouds from space. You can follow his spaceflight training on his Web site.