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Date: Wed, 29 Nov 1995 16:30:02 -0800
Message-Id: <199511300030.QAA06886@freefall.freebsd.org>
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From: J Wunsch <j@uriah.heep.sax.de>
Subject: Re: misc/848: Inst gripes about geometry but won't accept true values FDIV040
Reply-To: J Wunsch <j@uriah.heep.sax.de>
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The following reply was made to PR misc/848; it has been noted by GNATS.

From: J Wunsch <j@uriah.heep.sax.de>
To: uhclem%nemesis@fw.ast.com
Cc: FreeBSD-gnats-submit@freebsd.org
Subject: Re: misc/848: Inst gripes about geometry but won't accept true values FDIV040
Date: Thu, 30 Nov 1995 01:10:24 +0100 (MET)

 As uhclem%nemesis@fw.ast.com wrote:
 > 
 > 
 > Interestingly, the internally computed values 2039x64x32 equal 4,175,872
 > blocks,  which is greater than 2707x19x81==4,166,073.  This looks (on
 > the surface) like a really bad thing, as we may have computed a block count
 > greater than the true size of the media, and then later the system will
 > attempt to write who-knows-what out there.  In the case of this particular
 > drive, the 81 sectors per track is the average rounded-down (according to
 > the data sheet), so there is some slop and the true user sector count was
 > 4,177,781 so even the "bogus" numbers still work. 
 
 For SCSI disk, libdisk rounds the true disk size (as obtained from the
 disk) down to what it thinks is the closest cylinder boundary below.
 No harm can happen for non-bootable drives.
 
 (For FreeBSD-only disks, you can even use the entire disk capacity
 with the ``dangerously dedicated'' option.  C/H/S is effectively
 ignored then.)
 
 However, i agree that the warning is bogus and confuses the users.
 
 -- 
 cheers, J"org
 
 joerg_wunsch@uriah.heep.sax.de -- http://www.sax.de/~joerg/ -- NIC: JW11-RIPE
 Never trust an operating system you don't have sources for. ;-)