A. ADS is a feature pack for Windows Server 2003, Enterprise Edition, and Windows 2003, Datacenter Edition, that lets you deploy Windows server OSs onto "bare-metal" servers over large installations. ADS provides several features, including the ability to
- use imaging technology to capture an image of a server as one file and store that file on a central server.
- use a Preboot Execution Environment (PXE) boot, which is similar to Microsoft Remote Installation Services (RIS), or other methods such as the Windows Preinstallation Environment (WinPE) to deploy captured images to new servers (known as "devices" in ADS terms).
- administer a virtual 3.5" disk from the ADS server for deploying BIOS updates, RAID configuration information, or other tasks that typically require the machine to boot from a 3.5" disk.
- create jobs to deploy to other systems (e.g., from the ADS server, you can perform a BIOS update, configure a RAID array, deploy an OS image, and run a script on 100 servers).
- mount images locally so you can modify them.
- use multicast instead of unicast (a RIS limitation) to perform bulk deployments of images, which minimizes network bandwidth.
- use the ADS Administration Agent from the ADS console to run commands, programs, scripts, task sequences, and Windows Installer packages from one server or a predefined set of servers with minimum effort.
- store configuration data in a Microsoft SQL Server or Microsoft SQL Server Desktop Engine (MSDE) database.
ADS consists of three services and also relies on DHCP to let PXE clients obtain IP addresses. The first, the Controller service, is the core service of ADS. It performs all communication with the appropriate database and provides information to the other services. The ADS administration inputs (e.g., the Microsoft Management Console--MMC--snap-in, Windows Management Instrumentation--WMI--interface, and command-line tools) need the Controller service to operate. The Controller service maintains records in a database for each ADS device (i.e., a server typically identified by its media access control--MAC--address). During the build process, the Controller service uses the Network Boot Service (NBS--explained in the next paragraph) to tell the PXE component to provide to the device the boot commands or images the device needs at each stage in the deployment process. In other words, the Controller service manages the task sequence for the install. The Controller service lets you group servers into sets so that ADS can manage them as one entity for deployment and post-deployment administrative functions. You can also use references to link sets together, thereby forming a hierarchy.
The second service, the NBS, works with DHCP to help the PXE client locate the NBS server. NBS includes the ADS PXE service, the ADS Deployment Agent Builder service, and the TFTPD service. The PXE service, which is part of NBS, can instruct the PXE client to download and boot an ADS deployment agent, boot a virtual 3.5" disk, or boot from the hard disk. With instructions from the Controller service, NBS is responsible mainly for building remote servers. To transfer data to these remote servers, NBS uses Trivial FTP (TFTP) in the TFTPD service. Because TFTP uses UDP instead of TCP, TFTP is connectionless and has little overhead--communication takes place over port 69. ADS's third service is the Image Distribution service. This service manages the storage of the OS images and the communication associated with images.
ADS uses two agents: the Deployment Agent and the Administration Agent. The Deployment Agent, which NBS boots over the network through PXE, uses a subset of Windows so you can deploy systems from the ADS server. The agent also lets you download a disk image from or upload images to the ADS server. The Deployment Agent executes XML-based instructions (known as "task sequences") for typical jobs such as disk partitioning, modifying the registry, and copying extra files. The Deployment Agent is basically a scaled-down version of Windows 2003 that runs in memory. This figure shows the Deployment Agent capturing an image.
The Administration Agent is a service on the deployed OS that you must install before you image the OS. The Administration Agent lets the ADS server use Active Directory Services Interfaces (ADSI), the WMI Command-line (WMIC) tool, or Windows Script Host (WSH) on the deployed OS. You can also use the Administration Agent to execute other third-party scripting engines.
ADS also includes several tools to capture, open, modify, and restore images. You can even use certain tools to create or deploy images without using the Deployment Agent (e.g., in the WinPE), although the Deployment Agent uses TFTP for better performance and is typically the best option. The main tools are
- Imgdeploy--Performs the image capture and restoration. When you restore an image, ADS captures local images on a file-by-file basis and defragments the image. Note that defragmentation doesn't occur when you perform a remote capture. In such instances, ADS performs a cluster-by-cluster capture; when you restore the remote image, any fragmentation that existed on the original system remains.
- Imgmount--Lets you mount an ADS image as if it were a local drive so you can modify the image.
- Adsimage--Lets you list and deploy images.
ADS is a powerful new addition to the Windows Server family. ADS should ease administration in many environments, even those that don't use ADS's deployment functionality.