Re: What no-one has mentioned yet... - DRUMS
When I visited the machine room in Claremont Tower at Newcastle University in 1978 or '79, they had a drum acting as the swap space on the IBM System/360 Model 65.
What I remember is that the side was replaced by a perspex panel, and you could see the multiple fixed heads arranged around the spinning drum, so there was no seek component of the access time, merely the rotation time of the drum.
At Durham, we had a PDP11/34e with RK05 drives in a DEC 19" rack , and when the drives were busy, the whole rack rocked forward and backward quite violently as the voice-coils moved.
Later, I looked after a system with 80MB SMD drives. The worst that we had happen was the platter brakes seizing, making one hell of a racket, and a minor head-crash. We did have one pack that had the bottom guard platter bent making it a little unbalanced, which used to sing, but we only used that to hold an infrequently updated system backup.