Understanding Modules and Disk Images

The benefits of a modular architecture are far-reaching. Thanks to modularization, when you need to add device drives, language packs, or service packs or make other updates, you can more easily introduce these new components because you are simply adding new modules to the system. When you need to update or remove an existing component, you can do so without impacting the system as a whole—the changes affect only the related module or modules for that component. Because language packs are separate modular components from the operating system itself, you don’t need a separate image for each language used in your organization, thereby reducing the total number of disk images large organizations need to maintain.

Microsoft reengineered the basic distribution format of the Windows operating system so that it uses a hardware-independent image-file format. The new imaging format is called Windows Imaging Format (WIM), and Windows Vista is distributed using this format. Thanks to WIM, Microsoft can ship a single binary to all of its customers around the world: one binary format for 32-bit architectures and one binary format for 64-bit architectures. WIM allows you to store multiple images in one file and significantly reduces image size by using a combination of compression and single-instance storage. With compression, the total size of the image file is reduced in much the same way as Zip compression reduces the size of files. With single-instance storage, the disk image contains only one physical copy of a file for each instance of that file in the disk image. This substantially reduces the size of the image because there are no duplicate files.

WIM allows administrators to modify and maintain disk images offline, which means that administrators can add or remove optional components and drivers or perform updates without having to create a new image. Administrators can also mount images as folders and work with them in much the same way as any other folder, making it easier to update files within images. For example, you can mount an image and then use Windows Explorer to update or remove files as necessary. The ease with which you can update disk images and the removal of the requirement to have multiple hardware-specific disk images greatly reduces deployment complexity and costs.

Creating and Managing Disk Images

At a high level, deploying Windows Vista with imaging requires the following procedures:

1. Creating the configuration to be deployed.

2. Preparing the system for capture.

3. Capturing the image.

4. Maintaining the image as necessary.

5. Applying the image.

Creating the Configuration to Be Deployed  Creating the configuration to be deployed means setting up the operating system, configuring the operating system, installing any necessary applications, and then configuring those applications. Once you do this, you can prepare the system for capture by running the System Preparation command-line tool (SysPrep.exe). SysPrep irrevocably alters the computer and designates it as a master deployment computer by removing the unique identification information from the computer.

By removing the unique identifiers from the computer, SysPrep creates a resulting image that can be installed on multiple computers without creating identification conflicts. However, the computer no longer has identifying information that allows it to be logged on to and used within a domain or workgroup setting. Typically, you must reinstall the operating system.

Capturing the Image  In the Windows Automated Installation Kit (Windows AIK), you’ll find a tool called XImage. Using the Windows Vista XImage tool, you can capture your image file from Windows PE or with the operating system fully loaded. The best technique for capturing an entire installation, however, is to use Windows PE. When capturing an image with Windows PE, no locked files or folders will be included in your installation image, and as a result, you should experience fewer problems capturing the image.

You can capture an image by using XImage with the following syntax:

ximage /capture ImageSource ImageDest "ImageDescription"

ImageSource is the location of the files to image, ImageDest is the name and location of the new image file, and "ImageDescription" is a description of the image file, such as

ximage /capture C:\Windows D:\WinVistaStandard.wim "Windows Vista Standard"

If you don’t specify a destination drive, XImage creates the image and stores it in the XImage folder on the system drive. If the image file is too large for your selected media, you can use the /split option to split an existing image file into smaller .swm files, such as for spanning across several CDs. Before you split an image, you must determine the size of the media required for the image and then provide this value as one of the parameters passed to XImage. In the following example, you split a previously created image file into 600-megabyte (MB) .swm files:

ximage /split D:\WinVistaStandard.wim 600

Maintaining the Image  Once you’ve created an image file, you can easily maintain the image. To do this, you must install the Windows Imaging File System Filter (WIM FS Filter) driver on your computer by right-clicking the Wimfltr.inf file in the XImage folder and then selecting Install. After installing the filter driver, you can mount image files to folders on your computer. The files in the mounted image can be browsed via the folder by using Windows Explorer or other software. You can perform copy, paste, and editing operations on files in the mounted folder without having to re-create the image.

Images can be mounted as read-only or read/write. Read-only images cannot be edited; read/ write images can be edited.

You can mount an image as read-only by using the following syntax:

ximage /mount MountPath ImageFilePath ReferenceNumber

MountPath is the location of the mount folder, ImageFilePath is the name and location of the .wim file to mount, and ReferenceNumber is the reference number of the specific volume in the .wim file to use, such as:

ximage /mount C:\Data D:\Images\Data.wim 1

You can mount an image as read/write by using the following syntax:

ximage /mountrw MountPath ImageFilePath ReferenceNumber

MountPath is the location of the mount folder, ImageFilePath is the name and location of the .wim file to mount, and ReferenceNumber is the reference number of the specific volume in the .wim file, such as:

ximage /mountrw C:\Data D:\Images\Data.wim 1

Using the mounted folder, you can:

• Open files and folders and view their contents.

• Add files or folders.

• Move the files and folders within an image.

• Edit existing files and folders.

• Delete files and folders.

When you have finished working with an image, you must unmount the image and optionally commit your changes. You use the following syntax to unmount an image and save your changes:

ximage /unmount /commit MountPath

MountPath is the location of the mount folder, such as:

ximage /unmount /commit C:\Data

If you mounted an image as read-only, you don’t need to use the /commit option. There are no changes to save.

Applying the Image  When you are ready to apply the image, you can do so using a variety of automatic techniques, such as deployment scripts, or you can apply an image manually. Either way, you must first prepare the target computer by creating and formatting the disk partitions. If you choose to perform these tasks from a script, insert the commands to create and format the disk partitions prior to executing the XImage commands that apply the image. You apply an image by using the following syntax:

ximage /apply ImageFilePath ReferenceNumber

ImageFilePath is the name and location of the .wim file to apply, and ReferenceNumber is the reference number of the specific volume to use in the .wim file, such as:

ximage /apply D:\Images\Data.wim 1

To have XImage apply and then verify the image, you can add the /verify option, as follows:

ximage /apply D:\Images\Data.wim 1 /verify