Re: '90s Called...
The '90s? Remember those washing machine-sized 20MB top-loading unsealed multi-platter drives that old DEC and DG boxes used? I recall some DEC guys experimenting with putting four sets of actuators and heads in those in the mid 1970s.
Cool idea, and interesting trying to come up with software which would take a read/write queue and optimally route the requests to the appropriate heads... on a machine with a 64K address space, no less.
This profession has always been a blast, and stays that way - as much fun as you can have with your pants on.