Task sequence: adding 'setting TPM in BIOS' step breaks deployment to C: drive

[Bram]

To deploy new devices, we're using a task sequence with BitLocker pre-provisioned.

So at the 'Partition Disk' step we added the BOOTPART and OSPART variable to the volumes and then added the OSPART variable to the 'Preprovision BitLocker' step and the 'Apply Operating System' step.

We also added a step which sets OSDPreserveDriveLetter to False as our Windows 7 WIM file is based on a D: disk drive file.

This all works out fine, all our devices have a BitLocker enabled C: drive.

 

Now we're looking into automating the TPM settings in the BIOS so we added a step which downloads a package and runs the HP bios tool and afterwards restarts the system to fully enable TPM.

This seems to break something as the boot partition becomes C: during the task sequence and the system partition becomes D: and at the end we end up with an installed OS on the D: drive.

 

I'm thinking of a few possible reasons why this is happening:

1. The BIOS step needs to download a package just after partitioning the disk step and needs a drive to store these files on so it chooses the first available volume which is the 300MB boot partition. Making this volume the C: drive. (Although we added the option 'Do not assign a drive letter to this partition' at volume level on the Partition Disk step.)

2. Restarting the system between the Partition Disk step and Pre-provision Bitlocker + Apply Operating System step, removes task sequences variables like OSDPreserveDriveLetter, BOOTPART and OSPART, breaking this solution. I've done a bit of googling but couldn't confirm this behaviour. Does anyone know what the effects of rebooting are on task sequence variables?

 

Anyone else an idea why this is happening or knows a workaround?

 

I've added a screenshot of our task sequence

 

 

 

[Bram]

Sometimes the solution is too simple to see it

I just added a second format & partition disk step to the sequence. This creates a temporary volume to download and run the bios tool.

After the reboot the old format & partition step starts with the variables and everything is good to go.