On 14 May, 09:45, "Wolfgang Kern" <nowh...@[EMAIL PROTECTED]
> wrote:
> Evenbit wrote:
....
> > I recall skimming a chapter in an edition of a Andrew S. Tanenbaum
> > textbook which described techniques for streaming audio/video data
> > from HDs by interleaving the sectors on which the data was stored
> > ( sec 1, sec 3, sec 5... then come back through and hit the even
> > sectors ) because one would have to wait for the platter to rotate a
> > full turn if you wanted to read consecutive sectors. It is all
> > probably outdated stuff nowdays what with HDs being almost entirely
> > virtualized.
>
> I think this were mainly* a timing issue back then.
> When I look at the now faster spinning drives (>=7200 rpm) this method
> or something similar may be still in use, perhaps just to (*)distribute
> the heat from write actions.
With modern discs which include inbuilt caches I would hope that any
given track is sucked into cache in one pass but I don't know if they
are. FWIW many years ago I felt that the same should happen to
cylinders. In other words all heads should read at the same time and
it should take no more than one rotation plus the rotation time of two
sectors to read an entire cylinder. Writes to a given cylinder could
be committed at the same time.
--
James
|
