Yes, you are correct, the 500GB is NVMe and the 2TB is SATA. No, there is no other SATA device. This machine is an intel NUC Hades Canyon, and just has two M.2 slots that I am using. SATA is in AHCI mode. 500GB SSD is a Crucial P1 NVMe and the 2TB is a Samsung 860 Evo M.2. No, I am not using Storage Spaces at all.   Thanks for your help!   Tim