First… what is a vhd?

A VHD is a virtual hard disk, essentially an image of a system and installed applications that runs on top of another environment.  It is also the format of the virtual hard disks used by Microsoft’s Hyper-V Hypervisor platform.

Ok.. so a VHD is a image of a system… why would I want to boot from it?

I had once thought that booting from virtual hard disks was a bit more work than just loading up a system and pressing the start button.  And indeed it is a bit more work, but in the end, for some it may be worth it.

Note: While it is not the goal of this post to go through the process of creating VHDs for boot, it is relatively simple to do (and can be done using the Windows 7 media).

Back to the why would booting from VHD be useful part.

Suppose you got a new system and it was running Windows 7 and had a fair number of the latest bells and whistles (64bit chip, lots of RAM, etc).  Rather than grabbing your binder full of CDs and loading them into this new system consider this for a moment.  Computers are only new for a short time, and the harder you use them, the more you might be inclined to format and rebuild.

What if there were a way to keep your base system as new as possible, and still run everything you need without crudding up the computer?

Suppose your system was freshly installed with Windows 7 and had no other applications on it (obviously reformatted or built from scratch).  If you create an image of the clean environment and store it on an external source and then create the obligatory repair disk you can keep your PC like brand new for a long time, as well as recover pretty much everything you use with very little work by booting to a VHD.

When you create the VHD, you will configure Windows inside the virtual hard drive and add programs like MS Office, Nero, iTunes, and the other gazillion things that are on your typical computer.  All of these things live within the VHD, which can be backed up to external storage.

Because Windows 7 allows you to choose the vhd as a boot environment, the copy of Windows running on the bare metal of your system is virtually never touched.  Sure there may be times, failed hardware, changes in config, random Sunday afternoon formatting, that cause your physical system stress and require a cleanup, but with a system image of the pristine environment of a brand new Windows 7 box and the repair disk, that is a snap.

Still sounds like more work

The setup is considerable, since a good many have licensing to take care of their needs for OSes or get PCs with a retail license already installed.  Given the return that the IT department will get on reduced repair time will be worth it because the “possibility” of a pristine image of Windows 7 being available for use is huge.

Being able to push an image out to a workstation and reboot into that image in a short period of time, depending on size of organization might be a very good trade off given the time it takes to deploy Windows and applications needed (even though Windows 7 has a shorter time to deploy than previous versions).

Something to consider

If your environment turns over frequently or needs methods for testing deployment scenarios this might be a great solution for your environment.  I encourage you to give booting from a VHD a shot, it might be a great time savings in the medium to long term.

What are your thoughts on deployment from a VHD?