Inaccessible Boot Device - XPN-1RU-M9 – Ross Video

A 1RU-M9-based system shows a blue screen (BSOD) error "Inaccessible Boot Device" when attempting to power up and boot the system.

The system will typically see all drives installed in the system, but the RAID is in a state where it is unable to be booted off of.

When prompted with the "Inaccessible Boot Device", check to ensure that the RAID has not been turned off.

How to Recover Volume

In BIOS, navigate to UEFI Drivers and select Intel(R) Virtual RAID on CPU

In the Virtual RAID section, you’ll see your RAID volumes and their statuses.
Select the failed volume and press enter
Scroll down to RAID Member Disks and select the first disk, and press enter
Click mark as normal.
If marking as normal does not work, you may see a mark as degraded option instead. This should also allow the system to boot Windows and finish rebuilding the drive. You will need to select a drive to mark as degraded when this comes up.
A new screen will appear asking to change the state of the failed drive to normal. Click yes.

Repeat steps 3-5 for the other RAID Member Disks and proceed to the next step when completed.
Go to UEFI Drivers > Intel(R) Virtual RAID on CPU (steps 1-2) and click Volume0
Click Reset to Normal if that is not an option, click Reset to Degraded
Degraded should still allow the machine to boot, just means the degraded drive will rebuild in Windows.
Go to Main and click Save Changes and Exit
It should boot to Windows - take note if any Windows Updates happen
Open up Intel(R) Virtual RAID on CPU and check that everything looks good there

Good practices after system drive failure:

After the rebuild is complete, search for and run Command Prompt as Administrator
Run sfc /scannow. Let it run to completion
Run DISM /Online /Cleanup-Image /RestoreHealth. Let it run to completion

If a system drive is missing after these steps, see the article below:
Missing NVMe System Drive in System RAID Volume - XPN-1RU-M9