Native VHD Boot Windows 10 Tech Preview

Interested in trying out the new Windows 10 tech preview but rather not partition your HDD/SSD? Native VHD boot will be your best bet. Basically you create a VHD, install the OS and boot from the VHD. If you want a better understanding of the concept take a look at this technet article: http://technet.microsoft.com/en-us/library/hh825689.aspx 

Before we begin I do want to add that this is not the only way to do it. In fact this can be done a bunch of different ways using the GUI etc. This was easy for my since I already had the Windows ADK installed and I've used the commands before.

Here are the steps I took to boot Windows 10 from a VHD using Windows 8.1

1. Download the Windows 10 Tech Preview


2. Download and Install the Windows ADK from http://www.microsoft.com/en-US/download/details.aspx?id=39982 


3. Create a VHD using diskpart
   
   Run command prompt as an administrator and type the following



 create vdisk file="C:\VHDs\Win10Ent.vhdx” type=fixed maximum=40000   
 select vdisk file="C:\VHDs\Win10Ent.vhdx”   
 attach vdisk   
 Create partition primary   
 Assign letter=w   
 format fs=ntfs quick   
 exit  



4. Mount the Windows 10 ISO
   
   

    Powershell  
    Mount-DiskImage -ImagePath "C:\ISOs\Win10Ent.ISO"  

   
   This will mount the ISO using the next letter available. In my case it was F:


5. Install Windows 10 to the VHD we created
   I was curious if there was more than one version in the Install.wim.
   
   

    C:\>dism /Get-WimInfo /WimFile:"F:/Sources/install.wim"  
    Deployment Image Servicing and Management tool  
    Version: 6.3.9600.17031  
    Details for image : F:/Sources/install.wim  
    Index : 1  
    Name : Windows Technical Preview for Enterprise  
    Description : Windows Technical Preview for Enterprise  
    Size : 13,064,126,543 bytes  
    The operation completed successfully.  
   


Only one version which makes our choice easier. Now let's install Windows 10 to our VHD


 C:\>dism /apply-image /imagefile:"F:/Sources/Install.wim" /Index:1 /ApplyDir:W:\  
 Deployment Image Servicing and Management tool  
 Version: 6.3.9600.17031  
 Applying image  
 [==========================100.0%==========================]  
 The operation completed successfully.  


Once the operation is completed successfully you will notice that if you browse the VHD it will have the directory structure of Windows.


6. Configuring boot options
   There are 100 different ways to do it but the easiest I found was to run the below command
   

    bcdboot W:\Windows  
   

   
   Now run bcdedit /enum to make sure the entry was created
   
7. Finally we will need to detach the VHD to prevent any corruption
   

    diskpart  
    select vdisk file="C:\VHDs\Win10Ent.vhdx"   
    detach vdisk   
    exit  
   


That's it. Now when you reboot you will notice that you can choose Windows Technical Preview. Enjoy!