Deploying Vista - Part 2: Understanding Windows Setup and the Windows Imaging File Format

by [Published on 2 April 2008 / Last Updated on 2 April 2008]

This series of articles on automating the deployment of Windows Vista to desktop computers continues with an overview of how Windows Setup works in Vista.

If you would like to read the other parts in this article series please go to:

In order to understand how to deploy Windows Vista, you need to first become familiar with the deployment concepts, technologies and tools found in the Windows Automated Installation Kit (Windows AIK). In the first article of this series, I gave you a quick bird’s-eye view of what the Windows AIK is and what it contains. Starting with this article, you’ll build your understanding of important technologies such as Windows Setup and the Windows Imaging File Format (the topics of this article) and the different configuration passes of Windows Setup (the topic of my next article). Then we’ll examine how to use tools like Windows System Image Manager (Windows SIM), the Windows Preinstallation Environment (Windows PE), the System Preparation Tool (Sysprep), ImageX, and Windows Deployment Services (Windows DS) to successfully perform deployments—plus we’ll also eventually cover how to use the Microsoft Deployment Toolkit 2008 (MDT 2008). But I’m getting way ahead of myself as we need to lay some groundwork first.

Let’s begin then with Windows Setup (Setup.exe), which is simply the program used to install Windows onto a computer. Using Windows Setup you can perform clean installations where there was no previous operating system; upgrades to previous versions of Microsoft Windows; and unattended (hands-off) installations. You can run Windows Setup directly from your Vista product DVD, from a custom-made Vista DVD together with an answer file, over the network from a distribution share, and so on.

What’s significant and new starting with Vista is that Windows Setup now uses Image-Based Setup (IBS), a new file-based disk imaging technology that uses Windows Image (.wim) files based on the Windows Imaging (WIM) file format. A .wim file contains one or more volume images of the Windows Vista or Windows Server 2008 operating system (a volume image is what you get when you capture a disk volume onto which Vista or W2k8 has already been installed) and you can perform various actions on these .wim files using tools like ImageX, Package Manager, and so on which we’ll discuss in due course.

If you open your Vista DVD in Windows Explorer, you’ll find two of these .wim files present in the \Sources directory (see Figure 1):


Figure 1: Boot.wim and Install.wim files in the \Sources folder on your Vista DVD

Here the boot.wim file is a default boot image while the install.wim file is (you guessed it) the default install image. Time for some terminology:

  • A boot image is an image you can use to boot a bare-metal system in order to begin the process of installing Windows onto the system.
  • An install image is a captured image of the installed Windows Vista or Windows Server 2008 operating system that can be applied onto your system.

Let’s make it clearer: you use the boot image to start the installation process, and once it’s running the installation process then applies the install image to the system you are installing Windows on. This explains why in Figure 1 above the install.wim file is so much bigger than the boot.wim file. Of course, both of these two images can also be customized in various ways, for example by adding drivers needed to support your system’s hardware. But I’ll get to that topic later on my series.

This new WIM file format technology provides a several advantages over previous Windows Setup technologies, namely:

  • You can install Vista on any hardware (as long as it’s the right architecture i.e. x86 or x64) since .wim files are hardware-agnostic.
  • You can service a .wim file offline, which means you can easily add drivers or updates to an image before using it to deploy Windows.
  • You can have multiple operating system images within a single .wim file. For example, a retail Vista DVD can have Vista Basic, Vista Home Premium, Vista Business and Vista Ultimate all stored in a single install.wim file on the DVD (your product key determines which edition of Vista you get to install). This is possible because WIM uses file compression and single-instance storage to reduce the space needs for doing this.

We’ll see later in another article how to make use of these two images for deploying Vista, but let’s get back to Windows Setup and look next at the Windows Setup process and how it works. I’ll focus on clean installs instead of upgrades as most enterprises use the former when they deploy Windows onto their client computers.

Three Phases of Windows Setup

Windows Setup in Vista takes place in three phases as follows:

Phase 1: Windows PE phase. In this phase you configure how Windows will be installed on your system, either by manually specifying information when prompted or by automatically providing this information using one or more answer files. The information you need to specify includes things like your Language, Time and Currency format, Keyboard or Input Method, Product Key (not needed when using volume licensed media), your acceptance of the EULA, which partition you want to install Vista on, and so on. Once this information has been supplied (manually or with answer files) the Windows PE phase of Windows Setup continues by configuring your disk, copying the install.wim file to your disk, creating the files needed to make Windows boot, and processing any answer file settings in the offlineServicing configuration pass (if there are any such settings). That may seem mysterious for now, but be patient as I’ll explain how configuration passes in my next article. Anyways, once all this is done the Windows PE phase is finished and the next phase of Setup can be begin.

Phase 2: Online Configuration phase. During this next phase Setup performs various configuration actions that make this new installation of Windows unique, such as creating unique Security Identifiers (SIDs) for machine and user accounts and so on.

Phase 3: Windows Welcome phase. The third and final phase of Windows Setup performs actions that prepare the operating system for use by the user. These actions include (in the following order) processing any answer file settings in the oobeSystem configuration pass (if there are any such settings), processing the Oobe.xml answer file (if there is such a file—more about this file in another article), and launching Windows Welcome on the computer. Windows Welcome is sometimes known as the Machine Out-Of-Box-Experience (Machine OOBE) as it’s what users see when Windows first boots on their computer. As the user walks through Windows Welcome he can perform final customizations such as creating additional accounts for his computer. You can bypass Windows Welcome if you like by booting Windows into audit mode, which lets you perform additional customizations such as adding drivers and installing applications. I’ll talk more about audit mode later on when we look at the preinstallation phases for successfully deploying Windows in enterprise environments.

Now that we have gained and understanding of what happens when Windows Setup runs, we’ll continue in the next article by examining the different configuration passes used by Setup.

If you would like to read the other parts in this article series please go to:

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