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Date: 	Mon, 8 May 1995 15:34:11 -0700 (PDT)
From: Tom Samplonius <tom@haven.uniserve.com>
To: Scott Mace <smace@metal-mail.neosoft.com>
cc: hackers@FreeBSD.org
Subject: Re: Is a 486 fast enough for SCSI?
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On Mon, 8 May 1995, Scott Mace wrote:

> >   I've got a AMD486DX4100 with an Adaptec 2940 and two SCSI drives.  When 
> > I run iozone on one drive I get about 1.9MB/s, but when I run a iozone on 
> > each drive I get about .9 MB/s (roughly half).  Since the SCSI bus runs 
> > at 10MB/s per second, the limiting factor appears to be the CPU?  I 
> > thought PCI devices required very little CPU time?
> > 
> 
> The limiting time is the speed of the drive.  I can get over 3megs/sec
> with my EISA bt747 and seagate barracuda drives.  And my cpu is only
> a 486DX2-66.  I'm never seen a single scsi drive actually do 10MB/sec.

  I realize that no SCSI drive can do 10MB/s, but it is clearly not the 
bottleneck when accessing two drives simultaneously, so what is?

Tom