Help with Windows 8.1 Update 1 Offline Deployment using MDT 2013

Question

Hi guys,
Hoping that someone has encountered this problem and that there is a simple solution that I am overlooking. Essentially the problem we seem to be having is that after the OS is installed the process of updating the boot partition incorrectly updates
the boot partition on the offline media, rather than on the local disk. Because UEFI requires boot media to be formatted FAT32 and our deployment is a little on the heavy side (upwards of 40GB) we are generating multi-partition boot media and
this seems to be creating a problem, our previous Windows 7 offline media (single NTFS partition) worked perfectly. 
By looking at the BDD.log I can see where it appears to examine the potential boot partitions, finds the local disk boot partition and the external usb hdd boot partition and chooses to write to the external. The task sequence restarts the machine shortly
thereafter at which point the device cannot boot with an error "No operating system found."
Thank you in advance for any assistance.

Answer 1

Hello Erik,
it seems to be a bug in MDT.
The routine in ZTIDiskUtility.vbs is looking for the last available boot device:
 For each oWMIDiskPart in AllDiskPartEx ( " WHERE Bootable = TRUE or BootPartition = TRUE " )
  oLogging.CreateEntry "Found bootable drive: " & oWMIDiskPart.Path_ , logTypeVerbose
  set oDiskPart = new ZTIDiskPartition
  set oDiskPart.DiskPart = oWMIDiskPart
  set oDisk = oDiskPart.GetDiskObject
  If oDisk.isOSReady( sOSBuild ) then
   set oLogical = oDiskPart.oWMIDrive( bForced )
   If isValidObject(oLogical) then
    If not bBootFiles then
     oLogging.CreateEntry "Found bootable drive (No Boot File Test) [ " & oLogical.DeviceID & " ]: " & oLogical.Path_ , logTypeInfo
     set GetBootDriveEx = oDiskPart
     ' My change
     Exit For
    ElseIf oFSO.FileExists( oLogical.DeviceID & "\ntldr" ) or oFSO.FileExists( oLogical.DeviceID & "\bootmgr" ) or oFSO.FileExists( oLogical.DeviceID & "\EFI\Microsoft\Boot\bootmgr.efi" ) then
     oLogging.CreateEntry "Found bootable drive [ " & oLogical.DeviceID & " ]: " & oLogical.Path_ , logTypeInfo
     set GetBootDriveEx = oDiskPart
    Else
     oLogging.CreateEntry "No boot files found: " & oLogical.Path_ , logTypeInfo
    End if
   End if
  End if
 next
I implemented an "Exit For", so you will get the first possible boot drive.