virtualbox.org

Host: Ubuntu 16.10 - Kernel 4.8.0-27 Generic
I successfully installed Windows 10 with VirtualBox 5.1.8 r111374 onto a 40 GB SAS virtual disk.

My issue is this:
When I attempt to boot to the newly installed operating system, I am dropped to an EFI shell because the virtual disks connected to the virtual SAS controller are offline (noticed during the install process I had to online the disk with diskpart). In my experience with physical nodes, this means that the SAS controller firmware is not bringing them online during its initialization which I usually fix by flashing the controller with an updated rom.

Is there any way to persuade the virtualbox SAS controller to online the disks, or is booting from SAS-connected drives unsupported under EFI? I couldn't find any info on this with a forum search.

I don't know about the SAS issue that you're facing, but you've got to remember that EFI is still noted as experimental, primarily for OSX guests. They've recently added USB boot from EFI, and fixed a bug where you couldn't boot from SATA if you had more than 2 ports occupied. Given how popular the last two examples are, I'm guessing that SAS booting has not been a priority, maybe that's why you couldn't find anything about it.

You could always head to the bugtracker and either search for an appropriate bug, or open a new bug report where you'll attach your logs and other vital information. It would also help if you can post the bug report number here so other can see the progress, add information, or see the final resolution.

On the other hand, I don't remember seeing anywhere that capability as being activated/advertised, therefore it's not a "bug" technically, it's a feature request/enhancement...

Not supported. Business case welcome.