Windows 7 - A Virtual Future

Eric Traut, one of Microsoft's chief operating system design engineers discusses VM technology.

Source: Core of "Windows 7" taking shape: meet the "MinWin" kernel

A virtual future

Traut, like most good engineers, is honest about the pros and cons of code that he works on. "I fully admit that there are some major problems in the Windows OS that are driving some of these [improvements in the core and virtual machine technology]" he said, in full self-deprecating mode. He reviewed some of the reasons one might want to run older operating systems in a VM, such as backwards compatibility and resource management. The idea, of course, has been around for a long time—Windows NT 3.1 ran older 16-bit programs in a VM called "Windows on Windows" or "WOW" for short. The technology has improved since then, however. Windows Server Virtualization, like VMWare ESX and Xen on Linux, will run in what is called "Hypervisor" mode, where a host OS is not needed. This greatly improves performance and can take full advantage of new on-chip VM hardware from companies like Intel. Parts of this technology will appear as "Viridian" as an add-on for Windows Server 2008.

Traut doesn't believe virtual machines are a panacea, however; he said that sometimes they could be used as a "crutch" to solve a problem that could be better addressed by improving the core of the operating system itself. However, in server applications, VMs are clearly an idea whose time has come. Powerful servers that can run multiple OSes at once can blur the line between traditional PC hardware and big-iron mainframes and increase the power of an existing datacenter.

Compatibility is another big advantage of VMs. Traut showed, just for fun, Windows versions 1.03, 2.11, "Classic" 3.1, and NT 4.0, running under Virtual PC. Few people need to run applications that are designed for these ancient operating environments, but the point was to demonstrate how VMs can solve even the trickiest of compatibility problems by simply running the entire OS that the application was written for.
If you don't want to sit through the entire one-hour presentation, istartedsomething.com has a handy nine-minute excerpt with the MinWin demo.


Later Ted