Geek of All Trades: No MED-V? P2V XP to W7 with MDT

Running an IT shop has always come with a side order of alphabet soup. That’s not likely to change any time soon.

By Greg Shields

Working with Windows has always required a veritable Ph.D. in acronyms. Combine virtualization’s acronyms with the alphabet soup of the free deployment tools from Microsoft, and suddenly this month’s column title starts looking like it’s missing a few vowels.

All kidding aside, the recent merging of virtualization technologies and Windows deployment is encouraging. One of these approaches uses Microsoft Enterprise Desktop Virtualization (MED-V). As part of the Microsoft Desktop Optimization Pack (MDOP—another acronym), MED-V creates an enterprise framework for deploying virtual PCs within physical PCs as a way to resolve application incompatibility.

MED-V “fixes” incompatibilities by running MED-V-incompatible apps within a Windows XP virtual machine (VM). That VM runs within the user’s physical instance of Windows 7.The incompatible app’s display and UI are seamlessly ported from the Windows XP VM to the Windows 7 computer. The user just sees an application that works and launches from Windows 7—and you’re now responsible for managing two OSes per user.

The Big E

True to the “E” in its name, MED-V is well-suited for the enterprise. It brings much-needed enterprise-wide administration functionality to large deployments. However, it comes at a cost—both in terms of software licensing as well as in the effort it takes to integrate MED-V into your environment.

MED-V absolutely works, but it can be a bit of overkill for deployments that don’t span across enterprises. Smaller environments don’t need far-reaching solutions when their problems are just a few users with incompatible applications. They need a simpler approach.

That simpler approach is the reason behind Microsoft P2V Migration for Software Assurance, which you can get from the Microsoft Download Center. While this tool tackles application incompatibility with the same approach as MED-V, it does so without the expansive MED-V architecture. It simply adds some functionality to the Microsoft Deployment Toolkit (MDT).

That functionality lets you virtualize a Windows XP computer the moment you upgrade it to Windows 7. Once virtualized, the Windows XP computer and its applications run within the Windows 7 computer. The key difference, however, is that managing the Windows XP instance—along with its policies, applications and configurations—is left to other tools.

MDT, P2V and Task Sequences

If that sounds confusing, a bit of background on the MDT may help. The collection of MDT  deployment tools creates Task Sequences for upgrading or refreshing an OS. An MDT Task Sequence represents a series of configurable steps that automate the many processes involved in installing Windows. Figure 1 shows an example of the different kinds of task sequences the MDT supports.

Figure 1 Task Sequences in the MDT

Figure 1 Task Sequences in the MDT

There are two commonly used Task Sequences: the Standard Client Task Sequence and the Standard Client Replace Task Sequence:

  • The Standard Client Task Sequence deploys an OS to an awaiting desktop. You’d typically use this to upgrade a desktop from one OS version to another.
  • The Standard Client Replace Task Sequence is similar to the first, but you’d use this when you just need to refresh an existing OS.

Depending on how you’ve configured the MDT and how you launch each sequence, you can use both sequences to capture user state information. This is what you’ll later inject into the upgraded OS after installation.

The Task Sequences do a good job with user state information, but do little for application compatibility. P2V Migration for Software Assurance automates this step. It automatically captures a copy of the existing Windows XP computer just before upgrading it to Windows 7. It then converts that copy into a virtual hard disk (VHD) file using the Physical-to-Virtual (P2V) process.

Once the machine is upgraded, it installs the VM on the Windows 7 computer and adds its applications to the Start Menu of the Windows 7 computer. Finally, it installs Virtual PC for Windows 7 on the physical computer to run the VM.

The P2V Migration Tool almost completely automates this process. The end result is two independent but colocated OSes (Windows XP and Windows 7) running on a desktop.

Get P2V Migration Going

There’s a short installation process required before you’ll see the P2V-related Task Sequences shown in Figure 1. Start by installing the P2V Migration for Software Assurance to your MDT server. This adds a series of update packages that are eventually installed on the desktops as they get a new OS. These updates add support for Virtual PC into Windows 7, and update the Windows XP instance to support RemoteApps, a Remote Desktop Services functionality that facilitates feeding Windows XP applications into Windows 7.

Now you’ll see two new Task Sequences in the drop-down list when you choose to create a New Task Sequence: Standard Client Task Sequence with P2V Migration and Standard Client Replace Task Sequence with P2V Migration. These two obviously relate to the previously explained sequences, with each adding the P2V step to the upgrade sequence.

To use either of these, you first have to create a New Task Sequence. Assuming you’ve already configured your MDT server with at least one image, click Task Sequence | New Task Sequence. Enter a Task sequence ID and Task sequence name in the first page of the wizard. Then choose the Standard Client Task Sequence with P2V Migration when prompted for a template.

The remaining steps to create the Task Sequence are similar to what you’ve done before. Select an OS image to deploy, enter product key information, supply OS settings and an administrator password, and eventually confirm the Task Sequence creation.

You use the same steps to launch the P2V Task Sequence as you would for a regular Windows deployment. At the Windows XP computer, start by browsing to the Scripts subfolder of your MDT deployment share. Double-click to launch the Litetouch.vbs script. As the script executes, you’ll select a task sequence to execute on this computer. Select the P2V Task Sequence and answer all remaining questions to start the process.

What Can’t It Do?

As you may imagine, a solution not intended for enterprise use won’t have the full bells and whistles. This is the case with the P2V Migration for Software Assurance tool. Before you consider using it, be aware of some of its more important limitations.

First, Microsoft intends this tool to be used for small deployments only. Jeremy Chapman strongly asserts this point in an excellent blog post on the tool. Remember also that P2Ving a system keeps that system around in your environment, even after you’ve upgraded the rest of your computers to Windows 7. By going the P2V route, you’ll be required to manage and maintain those now-deprecated systems even after you’ve tried to get rid of them.

Before choosing P2V, you should always explore the Microsoft Application Compatibility Toolkit (ACT). The ACT uses a series of software shims to “fix” incompatible applications. Working with those shims requires more up-front effort. That effort is rewarded, however, by actually fixing the application to run atop Windows 7, rather than keeping it safely within Windows XP.

Virtual PC, the Windows 7 application that runs your Windows XP VMs, also has a hard limit on VHD disk sizes. A VHD disk used with Virtual PC can’t exceed 127GB. Thus, any disk originally provisioned with a larger size won’t automatically work. This can introduce big problems if your Windows XP computers are configured with large disks.

Windows licensing and activation can also be a problem with this solution. While the name of the tool includes the words “for Software Assurance,” the tool is by no technical means limited to Software Assurance (SA) customers. You can use any instance of Windows you can legally P2V to a virtual system with this tool.

However, only OSes installed using volume licensing (like those from SA) will enjoy full automation. With others, at the very least you’ll have to manually reactivate the license after P2V conversion. There are additional limitations and known issues documented in the tool’s release notes.

More Acronyms, More Functionality

Notwithstanding its limitations and extra acronyms, the P2V Migration for Software Assurance tool is a useful addition to the Windows Jack-of-all-trades arsenal. It’s far from the enterprise virtualization solution MED-V, but that’s also one of its strengths. With a fairly simple download, and simple installation and usage, you can use the tool to quickly resolve application compatibilities that might otherwise derail a Windows 7 upgrade project.

You must remember that using P2V for old Windows XP computers will keep them around for a while longer. Use this tool as a last resort, but keep it around just in case.

Greg Shields

Greg Shields*, MVP, is a partner at Concentrated Technology. Get more of Shields’ Jack-of-all-Trades tips and tricks at*


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