HDD ...

From: Allison J Parent <allisonp_at_world.std.com>
Date: Sun May 3 17:52:41 1998

<With all this talk of hard drives slicing themselves and adjacent
<walls to pieces, how is it that the motor can spin up to such a
<high speed when it's not supposed to, and why doesn't the head
<dragging on the disk surface cause it to stop?

Head draging...? only if it's crashed even then the motors on those old
drives were huge.

<Can any of these stories happen to a modern drive?

Less likely as smaller platters, less mass and more exotic speed control
servos. The big difference is that you would need som really amazing RPM
to make a 3.5" plater fracture and fail where a 14" platter has a far
higher speed at the perimeter at a lower RPM. Without running the numbers
a 14" platter goes transsonic at the perimeter at something like 14,000
RPM however before you get to that speed the forces working on the metal
are high enough that it will exceed the tensile strength. Also small
imbalances show up with increasing rotational speed and the platter start
to develop vibratory waves which if allow to go to destructive extremes
make for good stories.

I know as I have an operating Morrow (thinkertoys) DISCUS with a 10mb
memorex(m101) 8" drive.

Allison
Received on Sun May 03 1998 - 17:52:41 BST