*BSD News Article 12500


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From: hm@hcshh.hcs.de (Hellmuth Michaelis)
Newsgroups: comp.os.386bsd.questions
Subject: Re: AHA1542B and Julian's drivers -- *how* many sectors per track?
Message-ID: <2061@hcshh.hcs.de>
Date: 7 Mar 93 20:56:58 GMT
References: <tih.731518700@barsoom>
Organization: HCS GmbH, Hamburg, Europe
Lines: 25

In <tih.731518700@barsoom> tih@barsoom.nhh.no (Tom Ivar Helbekkmo) writes:

>The SCSI disk has
>(physically) 1224 cylinders, 15 tracks per cylinder and 36 sectors per
>track.
>[...]
>Then I installed Julian's SCSI drivers, and now I get something
>interesting: At boot time, the driver claims that my disk has only 34
>sectors per track!  That seems reasonable, considering that I couldn't
>use all of it with the geometry I set up, but *why* does it come out
>that way?

SCSI disks are able to fix bad sectors by themselves (if you program them
to do so) and leave some (programmable amount of) sectors unaccessible
for the outside world to remap bad sectors in case of failiure.

have a look at the manufacturers specs (and scsi command set) for your drive,
btw, julian's driver (at least for all drives i tested) is correct in it's
calculation of the resulting geometry.

hellmuth
-- 
hellmuth michaelis    HCS Hanseatischer Computerservice GmbH    hamburg, europe
hm@hcshh.hcs.de              tel: +49/40/55903-170          fax: +49/40/5591486
[ the opinions expressed above are my own and not the opinion of anybody else ]