PeachParts Mercedes-Benz Forum - View Single Post

kknudson · #23 03-08-2010, 03:25 PM

Interesting information about hard drives, back in the late 70s my boss went to the NY IBM R&D center. He came back with a book; I wish I’d have saved it.

The heads are flying; the spinning platters create a cushion of air that lifts the heads. That’s why when there is a power fail you can have a drive crash as that cushion disappears.
The book showed the gap the heads fly over the platter, a molecule of smoke was roughly twice the size of that gap.
It equated the heads flying to roughly the equivalent of flying a 747 at the speed of sound 18 inches off the ground.

The first HDs I worked with, the heads were actually hydraulically actuated, had one time my boss started pound on the window to the computer room. There was a tiny stream of oil spraying out of the drive onto the window.

The new Winchester drives are magnetically operated, using what basically is a speaker coil. The book explained that there really are only two speeds, full forward and full stop.
Something like driving from stop light to stop light where you stomp the gas, and stomp the break and always stop right on the line.

In the late 90s I worked with a company that produces diamond polishing compounds, mostly for very high tech applications. Although including the auto industry to hone cylinders (brake and engine).
The interesting point was in their specialty inventory section, each grit was color coded, until you got to the last 2 shelf’s, which had very small containers and plain.
The molecule of the color was smaller then the diamond molecule for polishing.
They were/are big supplies to the drive manufacturers, mostly for polishing the heads.
And the owner commented if you took cigarette ash, ground it with your fingers as fine as you could, it would barely make it to the top 3 shelves (there were 8 or 10 as I recall) as far as grit level.

Storage technolgy still fasinates me, having spent much of my IT career as a DBA or something similiar.