How do I run Windows on a VHD?

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How do I run Windows on a VHD

Running Windows on a virtual hard drive (VHD) can be useful for testing new OS versions or running multiple OSes on one machine. A VHD acts like a separate physical hard drive that can be attached to a Windows installation. This allows you to have a separate Windows install that runs independently from your main OS.

There are a couple ways to go about running Windows on a VHD. You can create a VHD within your existing Windows install and then install Windows to the VHD. Or you can attach a pre-created VHD containing Windows to your current OS. We’ll cover both methods below.

Requirements

Here’s what you’ll need before getting started:

  • An existing Windows machine. This will serve as the host OS.
  • Enough storage space for the VHD. Plan for at least 60GB if you’ll be installing Windows fresh onto the VHD.
  • The Windows ISO file you want to install if creating a new VHD. This can be for the same or different Windows version as your host OS.
  • Administrator access on the host Windows install.

The process of running Windows on a VHD involves a few key steps:

  1. Create a VHD file using Disk Management or PowerShell.
  2. Attach the VHD in Disk Management.
  3. Install Windows to the mounted VHD (for new VHDs).
  4. Boot from the VHD to start using the separate Windows environment.

We’ll cover each of these steps in detail in the sections below.

Method 1: Create and Install Windows on a new VHD

This method involves creating a brand new VHD file within your current Windows environment, then installing and configuring Windows on the VHD. Here are the steps:

Step 1: Create a VHD file

First, you need to create a VHD (virtual hard disk) file that will serve as your virtual drive. This is easy to do through Windows’ Disk Management utility:

  1. Open Disk Management (press Windows key and search for “create and format disk partitions”).
  2. In the lower portion of the Disk Management window, right-click anywhere in the empty space and select “Create VHD”.
  3. In the “Create Virtual Hard Disk Wizard” that opens, click “Next”.
  4. Choose “VHDX” as the disk format.
  5. Set the desired size for the disk. 60GB or larger is a safe bet for a Windows install. Click “Next”.
  6. Specify a location to save the VHD file, such as “C:\VHDs\Windows10.vhdx”.
  7. Accept the defaults to make this a dynamically expanding VHD file. Click “Next”.
  8. Review your settings and click “Finish” to create the VHDX file.

You can also create a VHD using Windows PowerShell. For example, this command would create a 60GB dynamic VHDX file:

New-VHD -Path C:\VHDs\Windows10.vhdx -Dynamic -SizeBytes 60GB

Either method will quickly create a virtual hard drive file ready to use.

Step 2: Attach the VHD

With the VHD file created, now you need to mount it so that it appears as a drive in Windows.

  1. Go back to Disk Management.
  2. Find the new VHD file listed in the lower pane.
  3. Right click the VHD file and select “Attach VHD”.
  4. The VHD will now appear as a drive letter under the Disk Management “Volumes” section, such as Disk 1, Disk 2, etc.

Attaching the VHD makes it accessible as if it were a physically connected hard drive. You can now proceed to install Windows on it.

Step 3: Install Windows on the mounted VHD

With your new VHD attached and accessible, you can go ahead and install Windows directly to it:

  1. Boot from your Windows installation media. This can be DVD, ISO file, or bootable USB stick.
  2. When prompted, select “Custom: Install Windows only (advanced)”.
  3. On the next screen you will see all connected drives and partitions. Select the mounted VHD.
  4. The Windows installer will prompt you to format the VHD. Click “Next” to do this.
  5. Installation will proceed normally. Windows files will copy over to the selected VHD.
  6. Once done, you can remove the installation media and boot directly to your new VHD Windows environment.

The process is very similar to installing Windows on a regular hard drive, except you are targeting the mounted VHD instead.

Step 4: Configure the new Windows install

Upon first boot to the VHD, Windows will go through its typical first-run prompts to configure settings, create a user account, etc. Make sure to:

  • Allow Windows to activate normally if the VHD version matches your host OS.
  • Give your Windows VHD install a unique name to distinguish it.
  • Create a password-protected admin account.

Once you complete the initial Windows setup, your virtual hard drive environment will be ready to use! You can access it alongside your host OS by rebooting and selecting the VHD from the boot menu.

Method 2: Use an existing Windows VHD

If you already have a Windows VHD image file, you can simply attach and boot from it instead of doing a full installation.

Here are the steps for this method:

Step 1: Verify VHD format

Make sure the existing Windows VHD uses the newer .vhdx format rather than the older .vhd type. VHDX includes features like 4K sector sizes that are required for recent Windows versions.

You can use PowerShell to convert a VHD to VHDX if needed:

Convert-VHD -Path C:\VHDs\Windows10.vhd -DestinationPath C:\VHDs\Windows10.vhdx

Step 2: Attach the VHD in Disk Management

As when creating a new VHD, you need to mount the existing VHD in order to access it. Follow the same steps outlined earlier to attach the VHDX file in Disk Management.

Step 3: Boot from the VHD

With the VHD attached, restart your host Windows environment. As it’s booting, bring up the boot menu (typically by pressing F8, F12, or a similar key). You should now see the attached VHD as a boot option alongside your main hard drive.

Select the VHD drive to boot directly into your separate Windows environment contained on the virtual disk file.

Using and Maintaining the Windows VHD

Once you have Windows running on a VHD, there are some steps to take for general usage and maintenance:

  • Boot between OSes – Use the boot menu at startup to choose either your host OS or the VHD Windows install.
  • Install software – Install and run any applications normally within the VHD environment.
  • Maintain and update – Check for Windows Updates and run an antivirus scanner periodically to keep the VHD secure.
  • Configure size – For dynamically expanding VHDs, use Disk Management to increase the maximum size if needed.
  • Back up data – Don’t store important data exclusively on the VHD. Use your host PC’s storage for critical files and backups.

The Windows VHD OS effectively functions like an independent physical PC. With some care and maintenance, it can be a very useful tool.

Benefits of running Windows on a VHD

There are a few great reasons to consider using a Windows virtual hard drive:

  • Isolation – The separate Windows install is isolated from your host PC’s configuration and data. This is great for testing software or OS upgrades risk-free.
  • Portability – VHD files can be moved between PCs more easily than cloning entire drives. You can bring your Windows environment to a new computer.
  • Backups – A Windows VHD file serves as an easy backup. Revert to a previous version if anything goes wrong with the host OS.
  • Virtualization – VHDs integrate seamlessly with Microsoft’s Hyper-V for running virtual machines. Use them as VM disks.

For technicians, developers, or power users who like to tinker with multiple Windows installs, VHDs offer some great advantages.

Potential downsides to running Windows on a VHD

Using Windows VHDs also comes with a few caveats to keep in mind:

  • Performance – Running from a VHD may result in slightly slower speeds compared to your main internal drive, especially if not using an SSD.
  • No hypervisors – This method runs Windows directly on a VHD rather than through a hypervisor like with proper virtualization.
  • Manual management – You will have to manually switch between the host and VHD OSes rather than seamlessly integrating them.
  • Boot complexity – Dual-booting can sometimes lead to boot issues that require repairing the BCD store.

These potential headaches can be mitigated by using a dedicated drive for your VHD file and keeping good backups. For many use cases though, the tradeoffs are worth it for the flexibility of having a portable Windows sandbox.

Conclusion

Running Windows on a VHD offers a flexible way to maintain a separate Windows install for testing, development, or other uses. The key steps are:

  1. Create a new dynamically expanding VHDX file or locate an existing Windows 10 VHD image.
  2. Attach the VHD using Disk Management so it mounts as a drive.
  3. Do a normal OS installation to the mounted VHD or boot from it directly.
  4. Use the boot menu to run either your host system or the VHD OS.

With those steps completed, you’ll be able to take advantage of the benefits of a fully portable Windows environment. Just be sure to factor in the potential downsides as well when planning your workflow. But overall, VHDs provide a handy tool for nearly any Windows power user.

Pros Cons
Isolated testing environment Slight performance impact
Portable Windows install No hypervisor management
Easy full system backups Manual dual-booting can be tricky