How To Guide to Installing and Booting Windows 8 Consumer Preview off a VHD (Virtual Hard Disk)

So Windows 8 Consumer Preview is out today. You probably read the Windows 8 Consumer Preview Announcement by Steven Sinofsky and then rushed off to Download it.

Disclaimer: Hopefully you are a technical person or you are not afraid of totally destroying your computer with new preview software. Even better, you aren't the kind of person to rage on a stranger's blog when his totally unsupported instructions on how to install the Windows 8 Consumer Preview onto a VHD delete everything you know an love. You're on your own, friend. I don't work for the Windows team and you don't know me. Remember that as you edit your boot records and destroy your PhD thesis. To the cloud!

First, what's the idea here? I'm assuming that:

• You want to try out Windows 8 on your machine
• You don't want to take any chance with dual booting or getting a slower experience inside a regular Virtual Machine.

Cool. If you have Windows 7 now then you can "boot to a virtual hard disk (VHD)" and get all the loveliness of Windows 8 running on hardware without any risk to your hard drive. Don't like it? Delete the VHD and update your boot record.

HUH? What does this mean? What this means is that ONLY the Hard Drive will be virtualized. Your Windows 8 system will run ON THE HARDWARE with your real video card, real CPU, real network card, etc. However, it will NOT run directly from your hard drive - it will run from a file on your hard drive. Windows 8 will live and run on its own personal "virtualized hard drive" which is the VHD.

Ok, now that that disclaimer and expectation setting is done. I don't work for the Windows team, and you don't know me. I am just a guy who loves Boot to VHD. I wrote the Guide to Installing and Booting Windows 8 Developer Preview off a VHD (Virtual Hard Disk) that you may have used last year to play with the build of Windows 8 that was released at the BUILD conference.

Updating from Developer Preview? Delete and start over!

If you want to now try using the Windows 8 Consumer Preview and you already have a VHD setup with the Developer Preview from last year, you can simply delete the existing VHD from your hard drive, then run "msconfig.exe" as administrator and delete the existing boot entry as seen in this screenshot.

Then just setup a new VHD all over again for this new Consumer Preview version of Windows 8. That's the magic of boot to VHD. You can just remove the VHD. You can even have multiple versions if you have the disk space. Just make sure your boot record is up to date.

Setting up Boot to VHD

The original instructions on how to boot Windows 8 from a VHD still work and are valid for the Consumer Preview. They work on my machine. I did want to slightly update the post with additional information with the help of a number of people internally with some techniques that may make things easier for you. Thanks to Iain and friends.

Why Boot to VHD?

I boot to VHD all the time. It works great, and the idea of booting to some VHD is a supported thing to be doing on Windows 7. Boot to VHD is a great actual feature of Windows 7 and Windows 8.  Why do it?

I could do a few things to work with Windows 8. I could:

• Try a virtualization solution, but it might not work, I may not have the drivers I need and it won't be as shiny as running "on the metal."
  • In fact, the Windows 8 team says this:  "Our recommendation for the Consumer Preview is to run it natively on hardware if you intend to run Windows 8 on hardware when the product is final. Some of you will run virtualized environments for enterprise workloads or specialized purposes, but we strongly recommend that you experience Windows 8 on hardware, as it was designed to run for the majority of consumer experiences. "
• Sacrifice a machine I have lying around. I'll probably do that at some point, but I'd like to try it out on my actual hardware that I use all day long.
• Swap out my C: drive and use my main machine. I don't have a tool-less case, and I'm also very lazy, so, um, ya.
• Dual boot. Dual booting may feel ninja but it ALWAYS ends on tears. And sometimes blood.
• Boot on real hardware from a Virtual Hard Disk

It's that last option that is the best one, in my opinion. Windows 7 included the ability to boot windows from a Virtual Hard Disk File (.vhd). You can read more about the Windows 7 VHD boot capability and recommendations from the TechNet article here. The Windows  8 developer preview was downloaded millions of times and the word on the street is that there was a huge increase in installations in virtualized environments. I think booting to VHD is way better than installing in a truly Virtual Machine because it allows Windows 8 (and you) to really access the native hardware and shine.

Requirements (read these!)

Here's the requirements if you want to try this.

1. You will need to be an Administrator on your Windows 7 system
2. You will likely need at least 40gb free disk space on the volume that the VHD is going to be stored. As you're likely creating your own VHD and installing Windows 8 Consumer Preview on it, then you will need free space at least equal to the virtual disk size of the VHD that was created
3. Boot VHDs need to be on an internal drive. USB drives won’t work.
4. If your system has Bitlocker enabled, you need to suspend Bitlocker while editing boot settings
5. More importantly, READ THE WINDOWS 8 CONSUMER PREVIEW FAQ!

Get Started

If you like doing things manually, you should directly the Windows 8 Consumer Preview ISO. I'd recommend burning Windows 8 Consumer Preview to a DVD or a USB Flash drive so you can easily install it on other machines easily. You can certainly do other ISO mounting tricks with other tools if you want to, but honestly it's just cleaner and easier to go download the Windows 8 Consumer Preview ISO and do it the regular way. There's less moving parts and all that.

From their site:

How to install Windows 8 Consumer Preview from an ISO image

The easiest way to convert an ISO file to a DVD in Windows 7 is to use Windows Disc Image Burner. On a PC running Windows XP or Windows Vista, a third-party program is required to convert an ISO file into installable media—and DVD burning software often includes this capability. One option is the USB/DVD download tool provided by the Microsoft Store. You can also download Windows 8 Consumer Preview Setup, which includes tools that allow you to create a DVD or USB flash drive from an ISO file (Windows Vista or Windows 7 required).

Take the Leap

Read the disclaimer at the top again. I don't know you and you're installing Beta software. .

Here's the general idea in broad strokes. The tiny details we'll be following are on my Guide to Installing and Booting Windows 8 off a VHD (Virtual Hard Disk).

• First:  Go Get the Windows 8 Consumer Preview Download

• Remember: Have a lot of disk space (40gigs or more)

• Either burn your downloaded ISO to a DVD or make bootable USB Key manually.

  • I detail making a USB key from an ISO in Step 1 on at my post, the Guide to Installing and Booting Windows 8 Developer Preview off a VHD (Virtual Hard Disk).

• Create a VHD that you will attach and install Windows 8 into

• Boot your system of your newly created Windows 8 Consumer Preview DVD or USB Key

• Attach your VHD during the setup process

• Select your VHD as the hard drive to install to (make very sure you know where you're installing to)

• Reboot and pick your operating system with the new lovely Windows 8 boot manager.

Alright. Sound good? You have some bootable media (DVD/USB) all setup with Windows 8 Consumer Preview? Now head over to my original post and start at Step 2. Fun!

Covering your Tush

If you want to be super careful you can backup your Boot Manager Database to a safe place by doing this from an Administrator Command Prompt:

BCDEDIT /export c:\bcdbackup.bak

and if you totally mess things up and you want to put things back the way they were, you can

BCDEDIT /import c:\bcdbackup.bak

Then delete the VHD and and reboot your system. If any of this is scary or you don't know what you're doing, then just stop and go here now.

FAQ

But I use the LILO (LInux LOader) or GRUB (Grand Unified Bootloader).Boot loader

By running the BCDBOOT command, you’ll set the Windows Boot Manager writes the entry to the Master Boot Record (MBR) of system as the default. A system can only have one Boot manager at a time.

If you want to revert to your previous boot loader, just follow that software’s normal installation instructions.

I've heard some reports of GRUB supporting .VHD boot, but we have not tested it. You're on your own.

Can I do this on a Mac?

No. Apple MacOS uses Unified Extensible Firmware Interface (UEFI) which locks the Guid Partition Table (GPT). The GPT holds a similar position in the UEFI systems as MBR for the BIOS systems.

Why does the VHD need so much space?

VHDs are created as dynamically expanding by default, up to 40gb which get expanded to their full size when used as a boot disk. Some people like them to be even bigger.

Note: The reason why the boot VHD gets expanded to its maximum size run running is to avoid the case where the hosting volume runs out of space when it is being actively being used as a system disk. If the hosting volume does run out a space, it would result in an unexpected system reboot. The user would need to boot into an alternate OS or recovery partition to free up space on the hosting volume before he can boot into the VHD again.

Can I use some other tools to do this?

There are a number of tools that do things like bcdedit in a graphical environment. I like Bellavista which I have used on Windows 7. However, do note that I did not test or run the steps above using anything but the tools in Windows.

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Hope this helps you have fun testing Windows 8 Consumer Preview in a safe way.