Creating USB Media for MDT installation with boot WIM > 4GB

Question

We have a working installation of MDT with the lastest AIK, which can successfully build laptops using a PXE boot. The objective is to be able to perform the build from USB media, to allow builds to tale place away from the office.

I have followed the steps in https://learn.microsoft.com/en-us/windows/deployment/deploy-windows-mdt/deploy-a-windows-10-image-using-mdt#use-offline-media-to-deploy-windows10 to create offline media. To give some information, the offline media that is created has two image files. One image file is the operating system to deploy, held under "Deploy\Operating Systems\WIN10REF2004-1" which is split into 1GB swm files, by the setting of " <SkipWimSplit>False</SkipWimSplit>" in the settings.xml file. The other image file is the one that is loaded into a Ramdisk when WinPE boots, and this ends up as "LiteTouchPE_x64.wim" in "Deploy\Boot", and is 4.8GB in size. The Total size of the deployment folder is about 35GB.

A couple of points to note:

1. The Total size of the deploy folder exceeds the maximum size of a FAT32 partition
2. The size of the boot WIM at 4.8GB exceeds the maximum size for a file in a FAT32 partition
3. Although I know that a UEFI PC can boot from NTFS if the Vendor provides the driver, the Lenovo X280 I want to build will not entertain booting from a 64GB NTFS formatted USB device
4. The Lenovo X280 will boot from a generic PE USB device

I have attempted to use Rufus to use UEFI NTFS disc creation, which loads in a driver for NTFS. I think this fails with insufficient memory to load Ramdisk (the laptop has 8GB RAM)

This seems to leave me in a situation where I have to have 2 partitions. A smaller FAT32 partition to enable the boot, and a larger NTFS partition to hold the majority of the Deploy folder. I can think of two possible methods to achieve this, neither of which I have been able to make work:

1. Split the boot WIM image and make PE boot from that. I have used DISM to split the WIM into SWM files and copied these onto the USB disc in place of the WIM. I consistently get device missing errors. To be honest, I do not know how to make the BCD point to these SWM files - at present the MDT offline build creates a BCD which references "device ramdisk=[boot]\Deploy\Boot\LiteTouchPE_x64.wim"
2. Make the boot process on the USB stick reference the 4.8GB LiteTouchPE_x64.wim in a location on the second (NTFS) partition. I do not know if this is possible

I would be glad of any suggestions on how to make this work, or of a better way

Answer 1

I have got past this now - I was trying to solve the wrong problem. The replies led me to considering why my boot WIM file was so large. Basically I had loaded too many drivers in the WinPE properties of the MEDIA entry in MDT. I changed this to select the WinPE x64 selection profile and only Network and Storage drivers, and the resultant WIM was about 600MB which does not cause this issue. I still have to use a 2 partition USB stick, but that is because of the size of the deployment share

Thanks for the replies

Answer 2

Hello there,

I had seen that article, but it does not address my particular issue. The article is a way to install a large reference image without splitting it. What I am trying to do is use the Offline Media created by MDT. In the MDT offline media my problem is not the custom WIM that holds my reference image - that is already split into .SWM files by MDT. The problem is the WIM file in \Deploy\Boot that is the PE image that the USB device uses as the OS image on boot (referenced in the BCD). That file is over 4GB, which means it will not fit on a FAT32 partition

Thanks