MDT and WDS working together
MDT vs WDS
To understand how MDT and WDS work to complement each other it helps to first understand the differences between these two systems.
Windows Deployment Services (WDS) is a server based technology used for deploying images of Windows operating systems and operates as a server role in Windows Server 2003 SP2, Server 2008, Server 2008R2, Server 2012, and Server 2012R2. WDS utilizes disk imaging and can perform network based installations of captured images which are typically stored in a .wim format. Image deployment over the network is accomplished through WDS’s use of the Preboot Execution Environment (PXE) to load a miniature version of Windows known as Windows Preinstallation Environment (PE).
WDS supports the management and deployment of driver packages which allows you to manage a variety of devices and architectures within your environment. However, it does not support the ability to deploy software or configuration changes during the deployment process. This necessitates the use of thick images which contain all software, configurations, settings, and updates pre-configured and set in your master image before being captured and deployed.
When operating as the primary deployment solution WDS functions as both a storage repository for the PXE network boot images as well as a repository for the actual operating system images to be installed on the target computer.
The Microsoft Deployment Toolkit (MDT) is a “solution accelerator” used for designing and creating operating system and application deployment. It is typically used in concert with the Windows Automated Installation Kit (WAIK) to produce highly customized and automated deployment solutions.
MDT supports a wide variety of deployment methodologies: Zero Touch Installation (ZTI) (Requires integrations with SCCM), Lite Touch Installation (LTI), and User Driven Installation (UDI). Each of these can be combined with either a thin image deployment or thick image deployment resulting in six available deployment scenarios.
MDT is a task based deployment process that offers unparalleled control over every step of the deployment:
- Complete management of device drivers – identify the model during deployment and inject only the necessary drivers for that model
- Run custom scripts
- Install software
- Dynamically keep images up to date by adding Windows updates
Due to the dynamic nature that MDT provides it permits the use of a small, clean, thin base image that can be added to during the deployment process based on criteria you identify ahead of time. Additionally, because software and settings are added during the active deployment process the need for multiple specialty images is reduced. You can deploy the same base image to two different areas and through the use of varied task sequences deploy a completely varied set of software packages and settings.
Simplified, WDS can capture thick images of your reference device and deploy that thick image with driver support to various devices within your environment using PXE. MDT is more of a design tool for creating a highly custom step-by-step deployment sequence.
MDT with WDS
It’s important to note that MDT in and of itself doesn’t have a true deployment system. You can create a Lite Touch Deployment USB drive with MDT and visit each device independently, but for true deployment capability MDT works best in concert with WDS. Some people ask the question: WDS is already a complete and standalone OS deployment solution, why not just use it for deployment needs? The answer is simply customization capabilities. MDT offers unparalleled customization options during deployment. We are also moving away from thick images as discussed in this article: Image Build Best Practices. Thin images offer numerous advantages to the imaging building process and lifecycle. So, a combination of MDT’s customization and WDS’s PXE deployment capabilities results in an ideal deployment solution.
MDT and WDS deployment process
To give you some insight into how the two technologies work together I have created the diagram above.
The process begins with the deployment workbench which can be a server or client device typically loaded with the Microsoft Deployment Toolkit (MDT) and the Windows Automated Installation Kit (Windows AIK). In older versions of the MDT two were required to successfully configure both 64-bit and 32-bit answer files. Modern versions of the MDT support both 32-bit and 64-bit answer file configuration. The deployment workbench will be were you setup, configure, and customize the settings on the deployment share. (The deployment share is a storage location located on your network capable of sharing files with devices you wish to deploy to).
Once MDT is setup and configured properly you will go through a finalization process of updating the deployment share. During this process you will generate boot images. Dependent on your setup these boot images will be 32-bit and/or 64-bit WinPE boot images that contain the necessary information to access the MDT deployment share. They will typically contain LAN drivers for the devices in your environment but may also include storage drivers as well. Once created these boot images will reside on the MDT Deployment share in the following location: \\MDT_Deployment_Share\Share_Location\WDS\Boot. These boot images can be used to make a deployment CD, deployment USB, or imported into WDS to implement true PXE booting capabilities.
MDT and WDS process flow
The MDT/WDS diagram illustrates the use of the two technologies in a Lite-Touch deployment scenario. For the purposes of this explanation the WDS server exists as a separate server and is not integrated with the DHCP server. You can read more on my thoughts on that topic here: PXE booting with WDS – DHCP Scope vs IP Helpers.
- Client/Server is powered on by tech/admin and F12 PXE boot is initiated.
- IP address is supplied by the DHCP server to the client
- Client broadcasts a PXE boot request
- IP Helper Forwards the PXE broadcast to the WDS server
- WDS presents boot image options – tech/admin selects appropriate Lite-Touch boot image – image is sent down to device
- The WinPE boot image requests deployment information from the MDT Deployment Share
- Tech/Admin utilizes the MDT Task Sequence selection menu and initiates deployment from the MDT Deployment Share for the desired OS
MDT is the star of the show
It’s worth noting that while WDS adds spectacular functionality with PXE booting, MDT is doing the real heavy lifting here. As soon as the WinPE boot image is downloaded, it immediately accesses the MDT Deployment Share and the remainder of the operation (over 90% – maybe more) is handled via the MDT Deployment Share. From a bandwidth and performance standpoint, this means that your MDT share should be a lot more powerful than your WDS server.
You can read more about MDT and the deployment process here:
I also recommend checking out Scriptimus Ex Machina – Andrew Barnes has some excellent MDT information there.