> SMD disks were first using 11" platters, later 8"; and with a nominal speed of 3600 rpm, thus 60 rotations per second (although Fujitsu later deviated from the norm and had a few drives spinning even faster, at 3961rpm), it took a noticeable amount of power to spin these disks up (and a smaller one to keep them spinning, which one would notice when receiving the bill from the electricity company).

I wouldn't mind having a few of these to act as backup flywheel batteries. Maybe if civilization crashes these will make a comeback as dual use power & data storage devices. ;)