Write Filters Support for Mass Deployment in Windows Embedded Standard 7
Mass deployment is the process of creating a master Windows Embedded Standard 7 runtime image on a reference system and then deploying this image to multiple target systems. The deployment process typically uses specific tools such as System Preparation tool (sysprep.exe) and Imagex.exe as well as Windows PE Environment to perform the following tasks:
- Generalize the master system by removing machine specific information
- Capture the system into a Windows image (wim) file
- Apply the image (wim) to the target system
- Specialize the image to the target machine.
Write Filters (EWF and FBWF) in WES7 are delivering sysprep providers to enable seamless settings transfer during mass deployment scenarios. These providers are part of the regular write filter (EWF or FBWF) packages. They are also invoked automatically when users run sysprep command, i.e. they do not require any user interaction. So, if a user is deploying a master image with FBWF protecting the system volume (C:) and having a folder (Documents) in the exclusion list, all target systems will end up protecting the system volume (C:) and having (Documents) folder in the exclusion list. Similarly, if EWF is protecting the system volume (Disk 0, Partition 1) of the master image, all target systems will end up protecting the system volume (Disk 0, Partition 1).
The main purpose of the write filter’s sysprep providers is to ensure transparent transfer of Write Filter settings from the master image to the target system, which is achieved as follows:
During Generalize phase, the providers remove unique per system identifiers – used by Write Filters to internally identify their protected volumes – and convert them into generic volume identifiers on the master image
- Converts FBWF unique volume identifier to its corresponding drive letter (e.g. C:)
- Converts EWF unique volume identifier to its corresponding disk/partition number (e.g. Disk 0, Partition 1)
During specialize phase, the providers reconstruct their unique per system identifiers from generic volume identifiers on the target systems.
- Converts FBWF the volume drive letter to its corresponding unique identifier
- Converts EWF disk/partition number to its corresponding unique volume identifier
When using an answer file with Sysprep, the write filter providers will check for any unattended WF settings in the file, if any are found, the providers will process these settings and merge all volume related ones into the target image. So, if the master image has EWF protecting Disk 0, Partition 1 and an answer file has Disk 0, Partition 2 in the protected list. After deployment both Disk 0, Partition 1 and Disk 0, Partition 2 will be protected. Similarly, if the master image has FBWF protecting the system volume (C:) and an answer file has volume (D:) in the protected list. After deployment both C: and D: will be protected.
- Target system must be identical to the system containing master image
- Write filters must be disabled (and system rebooted) before running sysprep
- Write Filter providers can only deploy volumes with drive letters
After mass deployment the write filter will be disabled on the target system(s) and users will have to manually enable it.
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