Unattended Installations

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Unattended Installations

When you perform server purposing using Automated Deployment Services (ADS), you typically deploy a master image that contains a fully configured Windows operating system. An alternative deployment option with ADS is an unattended installation.

An unattended installation is a scripted operating system installation that runs Windows Setup locally on the device using an answer file. The solution provides sample scripts that perform the preparation steps and operating system deployment. The process differs from the more typical network-based installations because the operating system installation files are delivered within an image instead of the using a CD or network shared folder.

An unattended installation is a two-phase process. In the first phase, operating system files and boot instruction are added to the Controller. A batch file - PrepImage.bat - is run and populates a partition with Windows installation and bootstrap files. The batch file then captures an image of the partition.

In the second phase, the image is deployed by running an ADS task sequence on a device connected to the Controller and using the Deployment Agent. During the sequence, the device that receives the image uses the bootstrap and installation files to run Windows Setup locally without intervention from an administrator or technician. Device variables are used during the sequence to personalize the installation (for example, to set the computer name).

The unattended installation deployment process is shown in the following figure.


Figure: An ADS unattended installation

There are several advantages to choosing an unattended installation.

  • Hardware components can differ for target devices - With an unattended installation, the ADS Controller deploys setup files to a device and the Windows setup process then runs locally on the device. During the setup process, hardware detection occurs. Any Windows-supported hardware will be installed and configured. However, deployment of a fully configured Windows operating system image to a device lacks this hardware flexibility. Devices receiving the image must essentially have the same hardware configuration as the server on which the master image was created.
  • Multicast support - The files needed for Windows setup, along with bootstrap files, are delivered to the target devices as an ADS image. By using an image, you can simultaneously deploy the unattended installation process to devices without impacting the network to the degree that a traditional, mapped drive would. Unattended installations of operating systems can occur to potentially hundreds of devices at the same time, a significant improvement over traditional, network-based, unattended installations.
  • Slipstream service packs and security updates - In an unattended operating system installation, the i386 directory can be updated with the most current service packs and security updates.

For more information, see Guide for Installing and Deploying Updates for Microsoft Windows Server 2003 and Windows XP 64-Bit Edition Version 2003 at Microsoft TechNet.

One drawback to an unattended installation is that each device takes approximately 30 to 40 minutes to run Windows Setup. In contrast, when an image configured with Sysprep is deployed to a target device using the typical ADS methods, it takes about 12 to 20 minutes to install a fully configured Windows operating system. In addition, the device in a typical deployment may also receive configured applications along with a fully installed Windows operating system. With an unattended installation, application installation must be scripted.

More Information

  • See for steps for implementing an unattended installation using ADS.
  • Sample scripts for implementing an unattended installation are located at Server Purposing\Sample Scripts\OS Unattended Install. You can also download the files at the Microsoft Solution for Windows-based Hosting Web site .