A bit of technology

First things first. Prerequisites:

• This is NOT for noobs! Your cat may die watching voodoo happening, be careful, use brain. And Google.
• Download Windows 8 Developer Preview for your platform (x86 and x64 are currently supported).
• You should have Windows 7 already installed. Don't know about Vista, but XP won't do for sure.
• Have some 40+ GB free on your HDD.

Part 1 - preparing

Create VHD. VHD - is a virtual hard drive in a file. It is used in virtualization software. The good news are that you can use VHD in your Win7 just like any other normal HDD. To create one open Computer Management and navigate to Storage –> Disk management. Now click menu Action –> Create VHD and you will see a small wizard. Put it somewhere like c:\vhd\w8.vhd. I will use this path through the tutorial. The size should be at least 40 gigs. Make it a dynamic disk or you will become old waiting for it to be created.

When your VHD is ready, mount it through Action –> Attach VHD. That will make your VHD visible to all apps as a new hard drive. Just like real one, but stored inside one file.

Now mount freshly downloaded ISO. Use Daemon Tools or an app of your choice. Open mounted ISO and VHD in your favorite file manager and copy contents from ISO to VHD. Just copy, nothing else is needed. The amount of data will be up to ten gigs. When copying is finished - move to the next part.

Part 2 - launching installation

Now is a bit tricky part. Reboot Windows to Recovery Console (use F8 at boot time). Recovery console will ask you to login to your Windows and will present a list of choices. Choose Command Prompt.

Depending on several factors your drive letters might change in recovery. That does not affect your current Windows installation, but you may not find c:\vhd\w8.vhd where you expect it. The easiest way to see drive letters is to launch Notepad. Just type notepad and hit Enter. Press Ctrl+O or navigate to File -> Open, choose My Computer and you will see all the drives with all the current letters. Close Notepad.

Now you need to mount your VHD. To do so you need to launch DISKPART. Type that into console and hit Enter. Now execute the following commands:

select vdisk file="c:\vhd\w8.vhd"
attach vdisk

When finished, launch Notepad once again and find a letter of VHD. It was letter F in my case. So next step is to launch W8 Setup. I typed f:\setup. Don't forget to change F to appropriate drive letter.

Part 3 - installation

We are almost done. The only thing left is to ensure that we are installing Windows 8 Developer Preview to VHD, not the real drive. To do so choose Custom Installation when prompted. If you choose Upgrade then you will loose your current system. That won't be good, trust me!

After choosing custom you will see a dialog showing all found HDDs and partitions. Select VHD one. Setup will tell you that it can't install to it. Don't trust him, just click OK and then Next. Installation will begin as usual and after lots of minutes and several reboots you will see big green screen - enjoy!



P.S.

To install Windows 8 Developer Preview this way I've read a couple of very useful tutorials written by Scott Hanselman. They also have lots of screen shots, so if you stuck somewhere - read them!

• Guide to Installing and Booting Windows 8 Developer Preview off a VHD
• Less Virtual, More Machine - Windows 7 and the magic of Boot to VHD