Drive constantly grinding ...

[Robert G. Brown]

On Sun, 15 Nov 1998, Justin T. Gibbs wrote:

> What you are hearing is likely what Seagate calls 'dithering'.
> When the drive is otherwise idle, the head is moved to new locations
> periodically so that it doesn't pass over the same piece of media
> for extended periods of time.  The Seagate representative told us
> (Pluto) that this was done to ensure that if a plater contained an
> imperfection that caused the head to 'brush' the platter occassionally
> (not a head crash) the head would not wear out the platter.  For
> real time applications (Pluto offers real time video editor/server
> products) where you want the head to stay where you put it, this
> is somewhat annoying.  Pluto's work around is to send a Test Unit
> Ready command to the drive every 500ms or so which restarts the
> 'diterhing timer' and prevents the extra seeks.

This is very interesting information.  If I understand it then, this is
a feature, not a bug, and will theoretically improve the lifetime and
reliability of your drive.  So if one can live with the per 5s whirr,
(and aren't doing real time applications) the best solution is just to
ignore it.

This is fine with me.  I really appreciate your passing the information
on.  I long ago decided that it was not likely to be a fatal problem,
but it is very comforting to know that it isn't a problem at all but
rather a deliberate design feature.

   rgb

Robert G. Brown	                       http://www.phy.duke.edu/~rgb/
Duke University Dept. of Physics, Box 90305
Durham, N.C. 27708-0305
Phone: 1-919-660-2567  Fax: 919-660-2525     email:rgb at phy.duke.edu




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