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From: Peter Dufault <dufault@199.232.245.2>
Message-Id: <199607280945.FAA01186@199.232.245.2>
Subject: Re: Setting disk sector size?
To: grog@freefall.freebsd.org (Greg Lehey)
Date: Sun, 28 Jul 1996 05:45:03 -0400 (EDT)
Cc: hdalog@zipnet.net, scsi@freefall.freebsd.org
In-Reply-To: <199607272253.PAA09896@freefall.freebsd.org> from "Greg Lehey" at Jul 27, 96 03:53:10 pm
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> 
> Since this is a used drive, we don't have any information about the
> jumpers.  Looking at the drive, I'd guess it's made by IBM, and it has
> very few jumpers.  I think I'm going to have difficulty following that
> possibility.
> 
> It seems to me that an obvious approach would be to try to write
> back the mode page and see what happens.  What command does that?

I think I've figured it out - I think you need to change it in
the block descriptor header instead of the mode page.  I found
this reference for an IBM drive with changeable geometry:

http://www-i.almaden.ibm.com/storage/techsup/hddtech/06614/06614mso.htm

And note that they specify the block length separately outside
of the mode pages:

> Changeable parameters are: 
> 
> Block descriptor 
>   Block length 
> 
> Page 0 
>   QPE (qualify post error) 

I have to leave here now - I have a ride waiting.  Later I'll put
together a script for you to change that if you don't have the
appropriate docs.

-- 
Peter Dufault               Real-Time Machine Control and Simulation
HD Associates, Inc.         Voice: 508 433 6936
dufault@hda.com             Fax:   508 433 5267