Quick and Dirty Image Factory with MDT and PowerShell

I haven’t written a blog in a while, been busy with the new job at Tanium, but I did write this script recently, and thought I would share, in case anyone else found it interesting. Share it forwards.


Been working on solutions to upgrade Windows 7 to Windows 10 using Tanium as the delivery platform (it’s pretty awesome if I do say so my self). But as with all solutions, I need to test the system with some end to end tests.

As with most of my OS Deployment work, the Code was easy, the testing is HARD!

So I needed to create some Windows 7 Images with the latest Updates. MDT to the rescue! I created A MDT Deployment Share (thanks Ashish ;^), then created a Media Share to contain each Task Sequence. With some fancy CustomSettings.ini work and some PowerShell glue logic, I can now re-create the latest Windows 7 SP1 patched VHD and/or WIM file at moment’s notice.


First of all, you need a MDT Deployment Share, with a standard Build and Capture Task Sequence. A Build and Capture Task Sequence is just the standard Client.xml task sequence but we’ll override it to capture the image at the end.

In my case, I decided NOT to use MDT to capture the image into a WIM file at the end of the Task Sequence. Instead, I just have MDT perform the Sysprep and shut down. Then I can use PowerShell on the Host to perform the conversion from VHDX to WIM.

And when I say Host, I mean that all of my reference Images are built using Hyper-V, that way I don’t have any excess OEM driver junk, and I can spin up the process at any time.

In order to fully automate the process, for each MDT “Media” entry. I add the following line into the BootStrap.ini file:


and the following lines into my CustomSettings.ini file:

    SKIPWIZARD=YES            ; Skip Starting Wizards
    SKIPFINALSUMMARY=YES      ; Skip Closing Wizards 
    ComputerName=*            ; Auto-Generate a random Computer Name
    DoCapture=SYSPREP         ; Run SysPrep, but don't capture the WIM.
    FINISHACTION=SHUTDOWN     ; Just Shutdown
    AdminPassword=P@ssw0rd    ; Any Password
    TASKSEQUENCEID=ICS001     ; The ID for your TaskSequence (Upper Case)

Now it’s just a matter of building the LitetouchMedia.iso image, mounting to a Hyper-V Virtual Machine, and capturing the results.


What I present here is the Powershell script used to orchestrate the creation of a VHDX file from a MDT Litetouch Media Build.

  • The script will prompt for the location of your MDT Deployment Share. Or you can pass in as a command line argument.
  • The script will open up the Deployment Share and enumerate through all Media Entries, Prompting you to select which one to use.
  • For each Media Entry selected, the script will
    • Force MDT to update the Media build (just to be sure)
    • Create a New Virtual Machine (and blow away the old one)
    • Create a New VHD file, and Mount into the Virtual Machine
    • Mount the LitetouchMedia.iso file into the Virtual Machine
    • Start the VM
  • The script will wait for MDT to auto generate the build.
  • Once Done, for each Media Entry Selected, the script will
    • Dismount the VHDx
    • Create a WIM file (Compression Type none)
    • Auto Generate a cleaned VHDx file


The code shows how to use Powershell to:

  • Connect to an existing MDT Deployment Share
  • Extract out Media information, and rebuild Media
  • How to create a Virtual Machine and assign resources
  • How to monitor a Virtual Machine
  • How to capture and apply WIM images to VHDx virtual Disks
#Requires -RunAsAdministrator
Auto create a VM from your MDT Deployment Media
Given an MDT Litetouch Deployment Share, this script will enumerate
through all "Offline Media" shares, allow you to select one or more,
and then auto-update and auto-create the Virtual Machine.
Ideal to create base reference images (like Windows7).
IN Addition to the default settings for your CustomSettings.ini file,
you should also have the following defined for each MEdia Share:
SKIPWIZARD=YES ; Skip Starting Wizards
ComputerName=* ; AUto-Generate a random computername
DoCapture=SYSPREP ; Run SysPrep, but don't capture the WIM.
AdminPassword=P@ssw0rd ; Any Password
TASKSEQUENCEID=ICS001 ; The ID for your TaskSequence (allCaps)
Also requires https://github.com/keithga/DeploySharedLibrary powershell library
[string] $DeploymentShare = 'G:\Projects\DeploymentShares\DeploymentShare.Win7SP1',
[int] $VMGeneration = 1,
[int64] $MemoryStartupBytes = 4GB,
[int64] $NewVHDSizeBytes = 120GB,
[version]$VMVersion = '',
[int] $ProcessorCount = 4,
[string] $ImageName = 'Windows 7 SP1',
[switch] $SkipMediaRebuild
#region Initialize
if ( -not ( get-command 'Convert-WIMtoVHD' ) ) { throw 'Missing https://github.com/keithga/DeploySharedLibrary' }
# On most of my machines, at least one switch will be external to the internet.
if ( -not $VMSwitch ) { $VMSwitch = get-vmswitch SwitchType External | ? Name -NotLike 'Hyd-CorpNet' | Select-object first 1 ExpandProperty Name }
if ( -not $VMSwitch ) { throw "missing Virtual Switch" }
write-verbose $VHDPath
write-verbose $VMSwitch
#region Open MDT Deployment Share
$MDTInstall = get-itemproperty 'HKLM:\SOFTWARE\Microsoft\Deployment 4' | % Install_dir
if ( -not ( test-path "$MDTInstall\Bin\microsoftDeploymentToolkit.psd1" ) ) { throw "Missing MDT" }
import-module force "C:\Program Files\Microsoft Deployment Toolkit\Bin\microsoftDeploymentToolkit.psd1" ErrorAction SilentlyContinue Verbose:$false
new-PSDrive Name "DS001" PSProvider "MDTProvider" Root $DeploymentShare Description "MDT Deployment Share" Verbose Scope script | out-string | write-verbose
$OfflineMedias = dir DS001:\Media | select-object Property * | Out-GridView OutputMode Multiple
$OfflineMedias | out-string | Write-Verbose
#region Create a VM for each Offline Media Entry and Start
foreach ( $Media in $OfflineMedias ) {
$Media | out-string | write-verbose
$VMName = split-path $Media.Root Leaf
get-vm $VMName ErrorAction SilentlyContinue | stop-vm TurnOff Force ErrorAction SilentlyContinue
get-vm $VMName ErrorAction SilentlyContinue | Remove-VM Force
$VHDPath = join-path ((get-vmhost).VirtualHardDiskPath) "$($VMName).vhdx"
remove-item $VHDPath ErrorAction SilentlyContinue Force | out-null
$ISOPath = "$($media.root)\$($Media.ISOName)"
if (-not $SkipMediaRebuild) {
write-verbose "Update Media $ISOPath"
Update-MDTMedia $Media.PSPath.Substring($Media.PSProvider.ToString().length+2)
$NewVMHash = @{
Name = $VMName
MemoryStartupBytes = $MemoryStartupBytes
SwitchName = $VMSwitch
Generation = $VMGeneration
Version = $VMVersion
NewVHDSizeBytes = $NewVHDSizeBytes
NewVHDPath = $VHDPath
New-VM @NewVMHash Force
Add-VMDvdDrive VMName $VMName Path $ISOpath
set-vm Name $VMName ProcessorCount $ProcessorCount
start-vm Name $VMName
#region Wait for process to finish, and extract VHDX
foreach ( $Media in $OfflineMedias ) {
$VMName = split-path $Media.Root Leaf
[datetime]::Now | write-verbose
get-vm vm $VMName <# -ComputerName $CaptureMachine #> | out-string | write-verbose
while ( $x = get-vm vm $VMName | where state -ne off ) { write-progress "$($x.Name) – Uptime: $($X.Uptime)" ; start-sleep 1 }
$x | out-string | write-verbose
[datetime]::Now | write-verbose
start-sleep Seconds 10
$VHDPath = join-path ((get-vmhost).VirtualHardDiskPath) "$($VMName).vhdx"
dismount-vhd path $VHDPath ErrorAction SilentlyContinue
$WIMPath = join-path ((get-vmhost).VirtualHardDiskPath) "$($VMName).WIM"
write-verbose "Convert-VHDToWIM -ImagePath '$WIMPath' -VHDFile '$VHDPath' -Name '$ImageName' -CompressionType None -Turbo -Force"
Convert-VHDtoWIM ImagePath $WIMPath VHDFile $VHDPath Name $ImageName CompressionType None Turbo Force
write-verbose "Convert-WIMtoVHD -ImagePath $WIMPath -VHDFile '$($VHDPath).Compressed.vhdx' -Name $ImageName -Generation $VMGeneration -SizeBytes $NewVHDSizeBytes -Turbo -Force"
Convert-WIMtoVHD ImagePath $WIMPath VHDFile "$($VHDPath).Compressed.vhdx" Name $ImageName Generation $VMGeneration SizeBytes $NewVHDSizeBytes Turbo Force


I’ve been struggling with how to create a MDT VHDx file with the smallest possible size. I tried tools like Optimize-Drive and sDelete.exe to clear out as much space as possible, but I’ve been disappointed with the results. So here I’m using a technique to Capture the VHDx file as a Volume to a WIM file (uncompressed for speed), and the apply the Capture back to a new VHDx file. That should ensure that no deleted files are transferred. Overall results are good:

Before:   19.5 GB VHDx file --> 7.4 GB compressed zip
After:    13.5 GB VHDx file --> 5.6 GB compressed zip


Gist: https://gist.github.com/keithga/21007d2aeb310a57f58392dfa0bdfcc2






Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out /  Change )

Google photo

You are commenting using your Google account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s