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How Unattended Installation Works

  • Article

Applies To: Windows Server 2008

This topic contains information about the process that takes place when you perform an unattended installation.

In This Topic

  • How Unattend Works for the Windows Deployment Services Client

  • How Unattend Works for the Remaining Setup Phases

  • Diagram of the Unattended Setup Process

How Unattend Works for the Windows Deployment Services Client

You can configure unattended installation based on per-computer settings or per-server settings (with per-computer settings taking precedence). The process works as follows:

  1. The Windows Deployment Services client starts networking and connects to the Windows Deployment Services server by using the remote procedure call (RPC) communication protocol. This entire transaction occurs over unauthenticated RPC because the client has not yet entered credentials.

  2. The Windows Deployment Services client sends information to the server that will help the server identify the client. This includes the values that are used to prestage the client (the computer's GUID or MAC address) and the client's architecture (because many settings are architecture specific).

  3. The Windows Deployment Services server determines the unattend file to send to the client. The server then queries for an account in Active Directory Domain Services (AD DS) that matches the GUID or MAC address.

    • If the device is found and has a specified Windows Deployment Services client unattend file, that unattend file will be used.

    • If the device is found but does not have a specified Windows Deployment Services client unattend file, the process continues.

    • If the device is not found (meaning that it has not been prestaged), the process continues.

  4. The Windows Deployment Services server checks its own unattend policy. This policy is defined globally and specifies whether Windows Deployment Services client unattend functionality at the server level is currently on or off. If it is off, no further action is required (as far as unattend is concerned). If it is on, the client will be passed the unattend file for its architecture.

  5. The Windows Deployment Services server reads the data from the client unattend file and then passes the data (not the file) to the client through the RPC communication channel. The Windows Deployment Services client receives the data, de-serializes it, and writes it to X:\sources\wdsunattend\wdsunattend.xml.

  6. The client notifies Setup about the unattend file, which triggers Setup to read the unattend settings and populate the relevant data. Setup then proceeds in Windows Deployment Services mode For more information, see “When Setup Is Started in Windows Deployment Services Mode” in How the Windows Deployment Services Client Works.

  7. At the conclusion of the Windows Deployment Services client installation phase, the Windows Deployment Services client unattend file is discarded and an image unattend file replaces it for the remaining phases of Setup.

How Unattend Works for the Remaining Setup Phases

The image unattend process works as follows:

  1. At the conclusion of the image apply phase, the Windows Deployment Services client copies the entire $OEM$ folder structure associated with an image (note that the $OEM$ structure is optional).

    • For Windows Vista and Windows Server 2008 images, this structure may contain the image unattend file, Be aware, however, that if an image unattend file was also directly associated with an image, the image unattend file will take precedence over the unattend file in the $OEM$ folder.

    • For images from an earlier version of Windows, the Sysprep.inf file should be placed in the $OEM$\$1\Sysprep folder.

  2. The Windows Deployment Services client queries the server to determine whether the image has an associated unattend file (for Windows Vista images only). If it does, the unattend file is copied to the RAMDISK of the boot image as X:\sources\wdsunattend\WdsImageUnattend.xml.

  3. The Windows Deployment Services client replaces the unattend variables and injects the domain join information into the temporary copy of the image unattend file.

  4. The client notifies Setup about the unattend file, which triggers Setup to read the unattend settings and populate the relevant data. Setup resumes in the OfflineServicing unattend pass.

  5. The computer reboots into the applied image. Setup starts in the applied image, locates the unattend file, and begins processing any remaining settings that are specified in the unattend file.

Diagram of the Unattended Setup Process

The following diagram illustrates the process that take place during an unattended setup.