I came across this video today which shows a tear-down of a suitcase-size heavy hard disk from the 1980’s that was used in a bank, which cost about $250,000 at the time.
Going by the video, the hard disk is an IBM 3390 model 2 and going by the linked IBM specification page, it appears to have a capacity of 3.78GB. it weighs 38.5kg, has 9 platters and requires an external controller as there’s no electronics in the hard disk apart from a small IC for each head.
The actual storage device for it would have contained 2, 4 or 6 of these hard disks and the controller, so the maximum storage capacity with 6 would give a total capacity of 22.7GB. The actual storage device would be similar size to a tall domestic fridge/freezer. Throughput was 4.2MB/s, 12.5ms average seek and 7.1ms latency. Going by the latency, its spindle appears to be about 4200RPM.
The video is quite long (43 minute) but well worth looking at the first few minutes.