Origin of "partition" in storage devices

[Paul Koning]

> On Feb 1, 2022, at 12:16 PM, Mike Katz via cctalk <cctalk at classiccmp.org> wrote:
> 
> In the rotating drive world there is constant linear velocity (CLV) and constant angular velocity (CAV) drives.
> 
> On CLV drives the speed of rotation would vary based on the track (slower in the inner tracks and faster on the outer tracks).  This meant that the data rate and number of bits/track remained constant.

Slower on the outer tracks, I believe.  CDs work this way.

> On CAV drives the rotational speed of the drive doesn't change, this means that the data rate and number of bits/track changes depending on the track.

It means that only if the sector count changes.  That's true for modern drives and for the CDC 6603; it wasn't true for quite a while.  A lot of "classic" disk drives have constant sector counts.  So, for example, an RP06 is a CAV drive and its transfer rate is independent of cylinder number since the sector count per track is constant.

I think hard drives are CAV as a rule because changing the spin rate as part of a seek takes too long.

	paul