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From: Robert Nordier <rnordier@iafrica.com>
Message-Id: <199607231145.NAA00292@eac.iafrica.com>
Subject: Re: anyone working on upgrading the msdosfs to NetBSD levels?
To: bde@zeta.org.au (Bruce Evans)
Date: Tue, 23 Jul 1996 13:45:25 +0200 (SAT)
Cc: current@freebsd.org, hackers@freebsd.org
In-Reply-To: <199607230808.SAA24449@godzilla.zeta.org.au> from "Bruce Evans" at Jul 23, 96 06:08:47 pm
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Bruce Evans wrote:
> 
> >myself.  However, the most serious FreeBSD msdosfs problem (where
> >it causes corruption to other partitions) apparently needs a
> >64-cluster FIPS-ed FAT filesystem with an EIDE controller translating
> >to 64 heads, 63 sectors to be readily reproducible.  (At least, I
> >haven't reproduced it on any other 64-cluster filesystems.)
> 
> I think you're saying that it is a hardware problem :-).
> 
> Bruce
> 

Over a few months, I've been collecting drive and DOS fs parameters
when users have reported corruption to *BSD partitions after
accessing (mounting/reading: not necessarily writing to) their DOS
filesystems using msdosfs.

The details I have (from 4 users) are summarized below.  Incomplete
details from 2 further users also indicate /dev/wd? and 400M+
partition sizes (but I'm not sure about the 64/63 geometry).

I don't currently have easy access to an IDE setup supporting more
than 16 heads.  Through fairly devious means, I have tried formatting
various DOS filesystems _as if_ they were originally created on such
as setup (and then FIPS-ed), but this doesn't reproduce the problem.

       DRIVE              DOS START        DOS END
       cyl  head sect ||  cyl  head sect   cyl  head sect      size
-------------------------------------------------------------------
wd0 |  525 | 64 |  63 ||    0 |  1 |  1 |  126 | 63 |  63 |  512001
wd0 | 2099 | 64 |  63 ||    0 |  1 |  1 |  189 | 63 |  63 |  766017
      same drive      ||  250 |  0 |  1 |  523 | 63 |  63 | 1104768
wd0 |  788 | 64 |  63 ||    0 |  1 |  1 |  787 | 63 |  63 | 3177153
wd0 |  621 | 64 |  63 ||    0 |  1 |  1 |  619 | 63 |  63 | 2499777

-- 
Robert Nordier