*BSD News Article 57969


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From: torek@elf.bsdi.com (Chris Torek)
Newsgroups: comp.unix.bsd.bsdi.misc
Subject: Re: SCSI disk geometries:  weird probe defaults are faster than custom!
Date: 3 Jan 1996 19:15:27 -0800
Organization: Berkeley Software Design, Inc.
Lines: 15
Message-ID: <4cfgof$1e7@elf.bsdi.com>
References: <4cf25e$m82@olympus.nwnet.net>
Reply-To: torek@bsdi.com
NNTP-Posting-Host: elf.bsdi.com

In article <4cf25e$m82@olympus.nwnet.net> Anthony D'Atri <aad@nwnet.net>
writes:
>... dumpfs complained about there not being room for the rotation
>tables.  This led me to discover that when one has disksetup [P]robe
>[this] disk, it defines the geometry [with 1 head, and 1 MB / `cylinder'].

As Terry Kennedy noted, the latter is deliberate.  This special
geometry forces sequential rather than rotational layout; for SCSI
disks (which are mostly ZBR these days) this generally results in
much better performance.

The complaint from dumpfs is a (minor) bug, fixed in 2.1.
-- 
In-Real-Life: Chris Torek, Berkeley Software Design Inc
El Cerrito, CA	Domain:	torek@bsdi.com	+1 510 234 3167