System Cloning Overview

Windows XP Embedded includes the System Cloning Tool component. The system cloning process is used during manufacture to ensure that each device has a run-time image containing a unique computer security ID (SID) and computer name.

If each device undergoes the stand-alone First Boot Agent (FBA) process separately, cloning is not required. However, the stand-alone FBA process is time-consuming and therefore impractical in a typical production environment.

If you simply copied the same post-FBA image to every device, every device would share the same computer SID. This presents a problem because every computer running Windows XP is required to have a unique computer SID. The solution is to include the System Cloning Tool component in your run-time image.

The cloning process consists of the following two phases:

Reseal phase
The reseal phase occurs on the device, which is called the master because the image created on it will be the cloned image. Typically, the reseal phase occurs just before the reboot that precedes the cloning phase; however, additional operations can occur between the reseal phase and the device reboot. After the reseal phase has completed, you must immediately shut off the device before the subsequent reboot would typically occur. At this time, the on-disk image is ready for cloning. For more information, see Reseal Phase.

Cloning phase
The cloning phase automatically begins the first time the image boots after the reseal phase, unless you set the extended property cmiResealPhase to 0 in Target Designer. Typically, this occurs after the on-disk image from the master has been copied to another device, or the clone. The clone device picks up where the master device has left off after the reseal phase. During the cloning phase, the computer SID from the master device is replaced with a unique computer SID everywhere the SID appears. This makes each clone unique where it is required but identical to the master everywhere else. The following illustration shows an overview of the cloning process.



During the cloning phase, you see a message in the Windows XP boot monitor stating that Windows is starting. This message notifies you that the cloning process is working. The amount of time spent in this phase depends on the size of the image and whether it is a FAT or NTFS file system. An image on an NTFS file system partition will take longer to clone because the NTFS file system uses SIDs to control access to each file system object using access control lists (ACLs).