Using P2V Migration for Software Assurance for Windows 7 upgrades

Talk to almost any IT administrator, and he'll speak of Windows XP as "the operating system that just won't quit." Despite its age and Microsoft's insistence that it be put out to pasture in favor of Windows 7, XP hangs in there.

Microsoft realized that it couldn't do away with XP in one swoop, so it has settled for inching it out incrementally. One key technology it deployed in Windows 7 to make this possible is Windows XP Mode, a virtual machine copy of XP that runs in Windows 7 through Windows Virtual PC. This allows users to install and run applications and hardware that require XP side by side with Windows 7 applications.

While this is a good option if you're deploying a new Windows 7 desktop and want backward compatibility with Windows XP, what if you have a XP desktop and want to preserve information going forward?

This is where P2V Migration for Software Assurance comes in.

It's a Solution Accelerator used with the Microsoft Deployment Toolkit 2010 to convert an existing Windows XP installation to a virtual hard drive (.VHD) file when the install is targeted for a Windows 7 (Enterprise or Professional) upgrade. It uses the Sysinternals utility Disk2VHD to perform the actual migration of the hard drive to a .VHD file (the utility will be automatically downloaded).

When the upgrade is finished, the old install of Windows XP is available in a virtual machine, and its applications are published into Windows 7's Start menu. The entire capture process is automatic.

As handy as P2V Migration is, it's bound by several limitations:

• P2V Migration is not licensed for use when migrating Windows XP installation that are OEM installations. Only installations licensed through Microsoft Volume Licensing or Software Assurance can be migrated to virtual machines.
• P2V Migration will only capture the contents of Disk 0 in the target system (typically the boot drive). Data on other drives will not be migrated, but multiple partitions on Disk 0 will be captured.
• P2V Migration will not work for an installation where the physical hard drive is larger than 127 GB. This holds true even for drives where the partitions are smaller than 127 GB; it's the physical size of the disk that's a problem here. (Windows Virtual PC cannot address a drive larger than 127 GB.)

Because of these challenges, Microsoft recommends physical to virtual (P2V) migration only in very specific circumstances, which are outlined and detailed by Windows Team Senior Product Manager Jeremy Chapman in a blog post. These circumstances include the following:

• The source media isn't available. This doesn't apply for OEM installations, since they can't be upgraded anyway, but rather for application installs or for custom-slipstreamed editions of Windows XP that may include exotic (or even custom-written) drivers or other elaborate installation configurations.
• Microsoft Enterprise Desktop Virtualization isn't available. That's what Microsoft recommends as the first line of approach for dealing with virtual machines, since Enterprise Desktop Virtualization is a lot more flexible and powerful than what Virtual PC can offer on a single desktop.
• The original installation can't be replicated for some other reason. Again, this could be because of third-party or custom applications with missing installation media or a hard-to-replicate setup process.

You shouldn't migrate more than a few machines in your organization with P2V Migration, and it's important to determine whether you really need to use the tool or if other upgrade paths would be more fruitful.

But P2V Migration can be handy for the desktops that might be nearly impossible to work with any other way.

ABOUT THE AUTHOR
Serdar Yegulalp has been writing about personal computing and IT for more than 15 years for a variety of publications, including (among others) Windows Magazine, InformationWeek and the TechTarget family of sites.