Windows Deployment Services

In Windows Server 2008, Windows Deployment Services (WDS) replaces Remote Installation Services (RIS) offered in previous versions of Windows Server. You can use WDS to perform "bare metal" installs (installations on computers without an operating system installed already) of base Windows operating systems without your being physically present or having access to the physical installation media. Instead, the system uses a combination of a pre-boot execution environment (PXE) and a Trivial File Transfer Protocol (TFTP) Server to boot the system from the network and load the operating system. This service provides an in-box solution that makes it easier for you to deploy Windows Server and Workstation operating systems throughout your organization.

WDS uses images created in Windows Imaging Format (WIM), a file-based imaging format unlike traditional disk imaging solutions that are sector-based. The advantage of WIM is that it is not hardware-dependent since the smallest unit within a WIM image is a file. In the WIM format, files are stored only once, even if they are referenced multiple times in the file tree. In other words, it leverages a single instance store. This makes the image smaller, and it is made even smaller since higher compression can be achieved on the files themselves. This image format is used by Windows PE (Preinstallation Environment) 2.0. Windows PE can be considered the replacement for MS-DOS as the boot environment for testing, installing, and deploying Microsoft Windows operating systems. It's a minimal install of a Windows system that is based on the kernel of the Windows operating system in addition to some necessary services.