Re: fuzzy disks, Is Parallel Programming Hard, And, If So, What Can You Do About It?

On 5/26/2025 1:31 PM, Scott Lurndal wrote:

Stephen Fuld <sfuld@alumni.cmu.edu.invalid> writes:

On 5/26/2025 10:42 AM, John Levine wrote:

According to Chris M. Thomasson <chris.m.thomasson.1@gmail.com>:

For some damn reason I thought of a fractal disk arm, an arm that had a
fractal structure, the disk rotates, but the fractal arm can read from
many places at once? Try not to flame me too much. ;^)

>
Dunno about fractal, but I have used head per track disks with a fixed arm
with many heads, and a disk with a crooked Y-shaped arm with two heads over
two tracks.

>
Yup.  And IIRC the IBM 3380 had a linear actuator with two heads per
arm, one covering the outer cylinders, the other the inner cylinders.
The tradeoff was shorter seeks, thus smaller seek time but higher cost
due to more heads.

 Burroughs had some memorex-built drives that had multiple actuators which
allowed it to sustain two simultaneous independent transfers from the
media.

Interesting.  I presume that the two transfers had to be to two different head of string/controllers.

This was circa 1988.  The drives were often shared between two
to four systems in loosely coupled multiprocessor configurations.

That makes sense.  No need to mess with the OS to allow two transfers to/from the same drive.

Ah, what's old is new again....
 I can't imagine why Seagate calls that "The world's first multiactuator technology",
given we had it four decades ago.

Come on, Scott!  Both of us old codgers learned long ago to separate Marketing from reality!  :-)  I'll bet 1988 was before many of Seagate's people were born, much less involved in the industry.
--
  - Stephen Fuld
(e-mail address disguised to prevent spam)