1. Windows Deployment Fundamentals
Since Windows Vista, operating system deployment in Windows
networks relies on a set of deployment tools and processes based on a
file format called Windows Imaging Format (WIM) and a lightweight
version of Windows called Windows PE. Many of these new tools, such as
ImageX, Windows SIM, and Copype.cmd, are made available in a free
toolkit called the Windows Automated Installation Toolkit (AIK). In
Windows 7 and Windows Server 2008 R2, support for WIM images and
Windows PE has been expanded through a new tool called
Dism.exe.
1.1 Understanding WIM Files
A WIM file contains one or more disk
images in the WIM format. Windows images are
file-based. This type of image isn’t a
sector-based snapshot of disk data, as is common with most disk
image types. Instead, Windows images are copies of the complete set
of files that make up a volume. The main advantage of file-based
images over sector-based images is that you can modify them before,
during, and after deployment.
Besides storing file data, WIM files include XML-based
metadata describing the files and directories that
make up each image. This metadata includes access control lists
(ACLs), short/long file names, attributes, and other
information to restore an imaged volume. Figure 1 shows the metadata
associated with a specific WIM file.
WIM files offer a number of advantageous features for
Windows deployment, including the following:
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Because the WIM image format is hardware-agnostic, you
need only one image to support many hardware configurations or
hardware abstraction layers (HALs). (Separate images, however, are needed for
x86 and 64-bit operating systems.)
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WIM files enable you to customize images by using scripts
or automate them by using answer files upon installation.
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The WIM image format enables you to modify the contents of
an image offline. You can add or delete certain operating system
components, updates, and drivers without creating a new
image.
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WIM files need to keep only one copy of disk files common
to all the images stored in the file. This feature dramatically
reduces the amount of storage space required to accommodate
multiple images.
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You can start a computer from a disk image contained in a
WIM file by marking an image as bootable.
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The WIM image format allows for nondestructive deployment.
This means that you can leave data on the same volume to which
you apply the image because the application of the image does
not erase the disk’s existing contents.
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A WIM file image uses only as much space as the files that
comprise it. Therefore, you can use WIM files to capture data on
a volume with empty space and then migrate the data to a smaller
volume.
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A WIM file can span multiple CDs or DVDs.
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WIM files support two types of compression—Xpress
(fast compression) and LZX (high compression)—in addition to no
compression, which is fastest.
1.2 Understanding Boot and Install Images
The \sources folder on every Windows product DVD since Windows
Vista contains two images: a default boot image (Boot.wim) and a
default install image (Install.wim). A boot
image is a relatively small Windows image (.wim) file you
can use to start a bare-metal client computer and begin the
installation of an operating system. By contrast, an install image
contains the actual Windows operating system to be installed.
Whether you deploy Windows through installation DVDs or over the
network, you can customize these boot and install images to suit the
needs of your organization and network.
The default boot and install images found on the Windows
Server 2008 R2 product DVD are shown in Figure 2. Note the
difference in the sizes of these two files.
