Booting from a virtual hard disk or VHD is a new feature shipping with Windows 7 and Windows Server 2008 R2. This post applies to both, client and server.
Booting from a VHD offers a variety of benefits for different scenarios.
We know VHDs or virtual hard disks from Microsoft virtualization solutions like Hyper-V, Virtual Server or Virtual PC. All solutions use the VHD as vessel for the OS. So does the boot from VHD feature. The main difference between boot from VHD and the other solutions is full access to the underlying hardware. Microsoft virtualization solutions – as well as competitors’ products – use virtualization to abstract the guest OS from the physical hardware.
Not so boot from VHD. The boot process has become more sophisticated and is now able to not only boot from a physical disk but also from a file. The file format conveniently is the same as for the before mentioned Microsoft virtualization solutions. That said, a VHD being created with any for the Microsoft virtualization solutions cannot be mounted and booted from without additional preparation.
The easiest way to create a bootable VHD to be used in a boot from VHD context is described below. A screen cast on TechNet Edge will be available soon.
Lots of stuff for additional blog posts later. Now let me finish the screen recording and get it up on Edge.
BCDEdit documentation Diskpart documentation Sysprep documentation VHD file format Hyper-V Virtual PC Virtual Server
BTW, here’s a snapshot of the setup I use to record the screen cast soon to be on TechNet Edge. Fun, fun.
My host is an Asus Eee 1000HE, a DVD drive is connected via USB and a SATA2USB dongle, the screen is recorded via Media Encoder and an Epiphan DVI2USB framegrabber connect to the VGA port of the Eee PC.