Path: utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!tut.cis.ohio-state.edu!att!att!cbnewsl!hojo
From: hojo@cbnewsl.att.com (HC Johnson)
Newsgroups: comp.sys.atari.st
Subject: Re: Q: spectre and 69MB harddisk
Summary: These Adaptecs seem to handle bad sectors very well
Message-ID: <1990Oct2.131933.18588@cbnewsl.att.com>
Date: 2 Oct 90 13:19:33 GMT
References: <1363@tnosoes.izf.tno.nl> <1990Sep28.195230.9880@cbnewsl.att.com> <3139@medusa.informatik.uni-erlangen.de>
Organization: AT&T Bell Laboratories
Lines: 32

In article <3139@medusa.informatik.uni-erlangen.de>, csbrod@medusa.informatik.uni-erlangen.de (Claus Brod ) writes:
> hojo@cbnewsl.att.com (HC Johnson) writes:
> 
> >(I solved this for controllers using the Adaptec 4000 and 4070 by writing my
> >own formatter, and giving the adaptec the bad sector list.  It maps them out
> >at the lowest level, leaving the partitions error free.).

Sorry to put a dialog here, but it has general application!

> How did you do that? I always thought the Adaptec controller couldn't do
> that because of a firmware bug - is there a trick?
> 

I have never heard of an Adaptec problem.  I have 2 Adaptec 4000A and the
Atari clone (in a SH204).  All of them properly accept the bad bit map
(could be called bad sector list) and map them out perfectly.  I know they
are doing it right because I have drives that completely died using the old HDX
and that is why I wrote my own formatter.

The Adaptec scheme completely maps out a bad sector, the sector numbers continue
in order, you just have fewer than the product of heads x sectors x cylindars.
The result is that ANY higher leverl program (partitioner) need not worry
about bad sectors.  (HDX 3.01 and other brands will play games with the TOS
format to work arround bad sectors; but MINIX and SPECTRE die.)

ps. this is better than my 6386 does -- it maps out a whole track for each
bad sector.

Howard Johnson
ATT BELL LABS
att!lzsc!hcj
hcj@lzsc.att.com