*BSD News Article 87545


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From: Kohler Markus <kohlerm@betze.bbn.hp.com>
Newsgroups: comp.os.linux.misc,comp.os.linux.setup,comp.unix.bsd.bsdi.misc,comp.unix.bsd.misc
Subject: Re: IDE vs SCSI (was Re: Linux vs BSD)
Date: 27 Jan 1997 10:02:05 +0100
Organization: Hewlett Packard GmbH Germany
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References: <32DFFEAB.7704@usa.net> <5c8a39$7tn@usenet.srv.cis.pitt.edu>
	<5c8odp$14q@ravel.cs.colostate.edu> <5c97cd$f6h@cynic.portal.ca>
	<5cblts$emh@junkie.gnofn.org>
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craig@gnofn.org (Craig Johnston) writes:

> 
> In article <5c97cd$f6h@cynic.portal.ca>,
> Curt Sampson <cjs@cynic.portal.ca> wrote:
> >In article <5c8odp$14q@ravel.cs.colostate.edu>,
> >Larry Pyeatt <pyeatt@.cs.colostate.edu> wrote:
> >
> >>While a modern SCSI system can sustain > 16MB/s  and my 5 year old
>                       ^^^^^^
> >>SCSI controller and drives can sustain > 8MB/s
>                       ^^^^^^
> >
> >Which SCSI drive do you have that sustains 16 MB/sec, and how did you
> >benchmark this?
> 
> I assume he's saying he's "sustaining" (in a totally unrealistic
> benchmark) 16MB/sec on his SCSI bus.  These "sustained" rates for
> big sequential reads are not really the most meaningful metric.
> They do give you some idea of what SCSI can do, however.  On a real
> OS, especially a loaded one, seek latency is prob. more important.
> Sustained rates for high-capacity EIDE drives (single) are probably
> similar to SCSI drives of the same capacity.  (excepting the high-end
> 7200RPM stuff -- do they even make EIDE drives this fast? )
> 

That's the problem. All high end drives i've seen have an SCSI interface. 

> It's things like tagged queueing and the ability to saturate your bus
> with multiple devices that make SCSI a win on real OSes.
> 
> -- 
> Craig Johnston, SysAdmin (but not speaking for), Greater New Orleans Freenet
> 
> http://www.gnofn.org    Free inet access for New Orleans and the Northshore.
> http://www.freebsd.org  Free 4.4BSD Lite derived OS for 386+ PCs. (just do it)

Markus

-- 
+----------------------------------------------------------------------------+
| Markus Kohler                          Hewlett-Packard GmbH                |
| Software Engineer                      Network & System Management Division| 
|                                        IT/E Success Team                   |
+----------------------------------------------------------------------------+