I once spent a good while trying to figure out why a 2U server wasn't recognizing new drives. No messages, no errors, no lights, nothing. Finally it turned out

I once spent a good while trying to figure out why a 2U server wasn't recognizing new drives. No messages, no errors, no lights, nothing. Finally it turned out that it's not a 2U server with 12 bays, but two separate servers in one box, side by side. Half the bays go to one, half to the other. Each side has two CPUs in it, and one was completely powered off.