Native Hard Disk Support in Windows 7

Windows 7 provides a unique capability, in that you can create, mount, and boot from a VHD file directly from the operating system, rather than requiring a software overlay, such as VirtualBox or ESX Server.

What this means is this: When dealing with most virtualization solutions, such as VirtualBox or VMWare, you need to install an underlying operating system (which controls the physical assets of your computer), then add in the virtualization software (VirtualBox, or the appropriate VMWare software), and then create and run a virtual Windows 7 system inside that. Think of it as a three-layer cake:

The bottom layer is the underlying operating system.
The middle layer is the virtualization software, which manages the VHD.
The top layer is your Windows 7 system.

Microsoft's native hard disk support for VHDs allows you to dispense with running a software overlay, such as the aforementioned VirtualBox or ESX Server. In this new model, your Windows 7 system manages its own virtualization, so there is no need for an underlying operating system and no separate virtualization software-all three layers of the cake are collapsed back into one layer.

So how do you create a VHD and install Windows 7 to it?

Creating a VHD

The simplest method is to use the Windows 7 installation DVD to create the VHD and then install Windows 7 into that VHD. Follow these steps:

1. Boot your system using the Windows 7 DVD.
2. Choose Repair Your Computer.
3. Click Next without selecting a particular destination.
4. Select Command Prompt.
5. Type diskpart and press Enter to start the Diskpart utility. Type create vdisk file="c:\Windows7Build.vhd" type=expandable maximum=40000 and press Enter.
   Tip: You can create any VHD filename you want, as long as there are no spaces in the filename.Note that the maximum parameter is the maximum size of the virtual hard disk in megabytes.You can make it larger if that is appropriate.
6. Type select vdisk file="c:\Windows7Build.vhd" and press Enter.
7. Type attach vdisk and press Enter.
8. Type exit and press Enter to quit Windows Repair. DO NOT REBOOT. Instead, click the [X] at the top right corner to close the Windows Repair window, and return to the installer.
9. Next, you create a partition in the new hard disk that you have just created. Start by clicking Install Now. When the License terms window appears, click "I accept the license terms"; then click the Next button.
10. Now click the option to install a new copy of Windows. You will be asked where you want to install the new copy of Windows. Choose the partition containing the virtual hard disk you just created.
11. Format the new hard disk partition by selecting the partition and then clicking the Next button. This also starts the installation process.
12. Install Windows 7 to this new hard disk.
13. Reboot to launch Windows 7.
14. After your Windows 7 installation is running the way you want, back up the VHD file. This provides a clean image of your system that can then be readily reloaded to your computer if needed.

Note: We've also found a number of other methods for creating VHDs and installing Windows 7 documented online by Windows developers around the world. Most of these are variations on creating a Windows system image (a WIM file) and converting it to a VHD, most often using the WIM2VHD utility available at http://code.msdn.microsoft.com/wim2vhd.We found literally thousands of results when we searched on the terms "Windows 7 create VHD."