I've never seen that Storagetek HDD unit before. I have seen the old IBM System 360 mainframe HDD units that had replaceable HDD disk sets on spindles. They looked like a stack of about ten 12" or 14" vinyl LP's on a single spindle, and that entire assembly was lowered into a drive unit nearly the size of an automatic dishwasher.
The open appearance of that unit and the one I described may shock some people. Yes, they really were open to surrounding air! The secret is they were NOT Winchester designs. All today's HDD's are Winchesters. They have heads mounted on semi-flexible arms. When the disk is at rest the heads actually rest on the disk surface. But when the disks are turning, a thin film of air carried along by the disk surface lifts the heads microscopically up and they do not touch anything. However, the gap is so small, any dust particle could get trapped under the head and gouge the surface, ruining both disk surface and head. So all Winchester disk deigns must be enclosed in a dust-free sealed container.
Those older drive units sminlal and I talk about were open, and the heads were on rigid arms that maintained a fixed clearance from the disk surface. The magnetic fields had to be much stronger to work over these larger clearances, so the data density was much lower, the data transfer rate much smaller, and the total capacity of the multi-disk unit much lower than later sealed Winchester designs.