Missing Registry Key PEBootRamdiskSourceDrive during WinPE

[Phi123]

Hello All,

 

I created a Windows 7 x64 based WinPE image with basic drivers for SSD.  This WinPE image is primarily used to capture/deploy Windows 7 image on a monthly basis.  I have DOS commands in startnet.cmd to automate this process.  When booting from USB flash drive, the script reads drive letter from "PEBootRamdiskSourceDrive" registry value in HKLM\System\CurrentControlSet\Control.

 

This has been working fine on existing USB flash drives - both USB 2.0 and 3.0.  I bought couple Kingston DTR3.0 G2 64GB flash drives recently... when I boot to these flash drive, the registry value with drive letter in PEBootRamdiskSourceDrive is not seen.  Registry value in PEBootType says Ramdisk:SourceUnidentified.  I am puzzled with this behavior and looking for clues.

 

Appreciate any tips / pointers.  Thanks!

[jaclaz]

Wild guess , mind you, but it is possible that those new sticks are set as "Fixed" media and this *somehow* affects the behaviour of the booting PE.

 

Basically 99.99% of USB 2.0 sticks are set in factory as "Removable".

 

Some of the fastish USB 3.0 are not anymore a USB stick, but rather a USB to SATA bridge with attached to it a SATA (miniaturized) SSD and they thus come as "Fixed".

 

Since all in all the drive letter is linked to the volume GUID in DosDevices and a hard disk like device (Fixed) uses disk signature+offset as identifier while a Removable device uses a different method, it is possible that the issue revolves around this.

 

Another reason might be if (for whatever cause) the wpeinit.exe is not executed.

 

Try running:

wpeutil updatebootinfo

https://technet.microsoft.com/en-us/library/dd744592(v=ws.10).aspx

 

And see if it makes a difference.

 

In any case you can check in the batch (which contains NOT "DOS commands" but rather Windows Command Line ones)  for the presence of a "tag" file in the available drives and set your variable with the drive letter resulting from the check.

Not entirely unlike we did in the good ol' times:

http://www.msfn.org/board/topic/137714-install-xp-from-a-ram-loaded-iso-image/?p=895361

http://www.msfn.org/board/topic/120444-how-to-install-windows-from-usb-winsetupfromusb-with-gui/page-72#entry1005836

 

jaclaz