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How Windows 8 could affect the future of Microsoft Hyper-V

With the release of Windows 8 approaching, a revised version of Microsoft Hyper-V will be included in both desktop and server versions. Find out what this new version has to offer.

Regular updates on the Building Windows 8 blog paint an increasingly detailed picture of what we can expect from Microsoft's next desktop and server operating system.

Perhaps no single entry so far has been as provocative or interesting as Steven Sinofsky's Sept. 7 post entitled "Bringing Hyper-V to 'Windows 8,'" which states that a revised version of Hyper-V -- based on the one included with Windows Server 2008 (and improved, somewhat, with the subsequent R2 server release) -- will be included in both desktop and server versions for this OS.

Let's explore what this new Hyper-V can do, why its inclusion in Windows 8 desktop versions matters and how it could affect deployments when Windows 8 becomes commercially available sometime in 2012.

What's up with Hyper-V?
Unlike earlier versions of Microsoft virtual machine (VM) software -- specifically, Microsoft Virtual PC and Microsoft Virtual Server -- Hyper-V is a true (Type 1) hypervisor, like VMware ESXi or Citrix XenServer. It can run directly on a physical computer's hardware to set up and manage guest operating systems. This is sometimes called a native or bare-metal hypervisor for that reason.

Until Windows 8 desktop comes along, none of Microsoft's desktop OSes has ever been endowed with a true hypervisor. Instead, they have had to rely on a virtual machine manager that runs as one program among many inside Windows. Windows Server 2008 gained this capability with the first version of Hyper-V, including a standalone version of Microsoft Hyper-V Server 2008 that works through a command-line interface via shell commands.

Later refinements in Windows Server 2008 R2 include a menu-driven interface where various management consoles may be downloaded to a Windows 7 or Windows Server 2008 R2 computer for use as a management console.

The release of Windows 8 promises to greatly expand the hypervisor's capabilities, in addition to bringing Hyper-V to the desktop. Here are some important upcoming features described in the Building Windows 8 blog entry cited earlier:

  • Windows 8 will be able to support "more than one 32- or 64-bit x86 operating system at the same time" on the same desktop.
  • Microsoft will release "preconfigured virtual machines containing old versions of Internet Explorer to support Web developers." Presumably, the same will hold true for other applications and perhaps even older operating systems.
  • Hyper-V's dynamic memory allows memory allocations to be raised and lowered as needed. Users can "run three or four VMs on a machine that has 4 GB of RAM but ... will need more RAM for five or more VMs."
  • Sinofsky states that Hyper-V can support "large VMs with 32 processors and 512 GB RAM," but that appears entirely aimed at the server side of the PC business. Today's beefiest workstation PCs top out at 12 physical processor cores and from 48 to 96 GB of RAM, so they're unlikely to test such limits. That said, it would be conceivable to create multiple VMs with two or four cores at their disposal with 4 to 8 GB of RAM for each one. This far exceeds current desktop capabilities.
  • The latest version of Hyper-V will support both virtual hard disks (.VHD or .VHDX files) and actual physical disks that are passed through to virtual machines. And because VHDs can reside across the network on a file server, this helps IT professionals to create and maintain a common library of VMs for shared use.

All in all, this means that powerful and usable virtualization technology is about to find its way onto at least some standard Windows 8 desktops.

Why Hyper-V on the desktop matters
Windows XP Mode provides access to a free Windows XP license running inside a Windows Virtual PC-based VM and is included in Windows 7 Professional, Enterprise and Ultimate editions. It proved that VMs can take the sting out of OS migrations. That's because they provide a relatively easy way to maintain access to otherwise incompatible legacy applications.

If old programs or code don't work on Windows 7 but run in XP, Windows XP Mode makes it easy to keep that legacy code running in a virtual machine environment even if the hardware has been replaced or its host operating system has been upgraded to Windows 7.

In Windows 8, Hyper-V throws open the doors to older Windows versions -- and even non-Windows operating systems -- in the name of continued application availability and access. But it does come with some limitations:

1.      Unlike Windows XP Mode, which gave away a Windows XP license to encourage its use, Hyper-V makes no such grants. Sinofsky's Hyper-V blog flatly states that "you will still need to license any operating systems you use in the VMs."

2.      The Windows 8 version of Hyper-V requires a 64-bit host operating system, and as the blog indicates, "Hyper-V requires a 64-bit system that has Second Level Address Translation." To check your CPUs, download Mark Russinovich's Coreinfo v3 Sysinternals utility. Intel Nehalem, Westmere, Bloomfield, Lynnfield or Sandy Bridge (all ix models, such as i3, i5 and i7) processors and AMD Barcelona (or newer) CPUs are required for Windows 8 Hyper-V to work.

Future deployment of Windows 8?
When Microsoft claimed that any hardware that could run Windows 7 would also be able to run Windows 8, it neglected to mention Hyper-V as a possible caveat. Of the three desktops and six notebook PCs I use for production and testing, for example, only one of those desktops (with an i7 930 CPU) and two of those laptops (one with an i7 720 QM and the other with an i7 2617M CPU) will be able to run Hyper-V in the upcoming Windows 8 release.

Several of my other machines, however, also include quad-core CPUs, 12 or more GB of RAM, and solid-state or fast-spinning hard disks that should support multiple VMs with ease.

Ultimately, a lot will depend on how important Hyper-V support becomes for users who wish to migrate to Windows 8 and run virtual machines and to maintain access to legacy code and applications. This won't be a problem for PCs that already meet the hardware requirements. But for the legions of PCs purchased before September 2009 -- or purchased afterward with older CPUs -- organizations will have to weigh the costs of a hardware upgrade carefully against the increased functionality that Window 8, especially Hyper-V, can deliver.

Ed Tittel
is a longtime computer industry writer with over 100 computer books and thousands of articles to his credit. His most recent book is Computer Forensics JumpStart. Read Tittel's IT Career JumpStart and Windows Enterprise Desktop blogs for TechTarget, as well as his weekly posts for

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