At 05:43 PM 1/4/01 , you wrote:
>> > I'm also still not sure how many ``some'' amounts to.  Is it commonplace,
>> > or rare?  Something that only expensive drives do?  (Most drives still
>> > have RPM numbers associated with them; if they achieve the differing
>> > densities by rotating at different speeds, then a single RPM is at best
> [...]
>> I'd say all modern drives have varying numbers of sectors per track... and
>
>So if a modern drive lists a single RPM rating, what (if anything) is one
>to make of that?  Average-per-cylinder?  Average-per-sector?  Minimum?  
>Maximum?  Or is it some kind of effective RPM (based on some nominal
>geometry and the speed at which a single block passes under the drive
>head)?
>
>> it's not that the data density really varies; the outside tracks have more
>> area, and hence can fit more sectors.
>
>Erm, yeah.  I was thinking roughly backwards.  (^&  (It's easier than
>thinking forwards, since you just have to follow the tracks...)
>

Check out http://storagereview.com/

Go to their reference section and look for the section on Zoned Bit Recording.
(http://www.storagereview.com/guide2000/ref/hdd/geom/tracksZBR.html)

Hope it's useful.  It's been a good site for me.


-Tim