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From: "Rodney W. Grimes" <rgrimes@GndRsh.aac.dev.com>
Message-Id: <199603120239.SAA13266@GndRsh.aac.dev.com>
Subject: Re: Slow Toshiba 6.7X cdrom drive.
To: joerg_wunsch@uriah.heep.sax.de
Date: Mon, 11 Mar 1996 18:39:50 -0800 (PST)
Cc: fcawth@jjarray.umd.edu, freebsd-scsi@FreeBSD.org,
        freebsd-hardware@FreeBSD.org
In-Reply-To: <199603112246.XAA00663@uriah.heep.sax.de> from "J Wunsch" at Mar 11, 96 11:46:04 pm
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> 
> As Fred Cawthorne wrote:
> > 
> > I just purchased a Toshiba 3701B 6.7X scsi drive.  I have the 3401 and I
> > like it, and the price was good...  Has anyone else had problems getting
> > this drive to work at full speed??  I get 300K/sec with a 486-66 and
> > an Ultrastor 14f controller.  I get 500K/sec with a 1542CF on a P-90
> > system.  I can get 1MB/sec with an NCR scsi controller on the pentium system.
> > What's going on here? 
> 
> Just for reference: i get 330 KB/s (only) from the 3401 on a 486/33
> with a Buslogic BT472A (EISA) controller (raw `dd' throughput).  The
> controller is known to get about 5 MB/s from the Seagate Hawk that's
> also in the machine.

Try the 3 following dd commands, I found that xfer rates on multispin
cdrom drives is heavily block size dependent.

dd if=/dev/rcd0a of=/dev/null bs=512
dd if=/dev/rcd0a of=/dev/null bs=2048
dd if=/dev/rcd0a of=/dev/null bs=8192

Many drives will due there highest rate with the 8K I/O, a few others
seem to like the 2K I/O. 

-- 
Rod Grimes                                      rgrimes@gndrsh.aac.dev.com
Accurate Automation Company                 Reliable computers for FreeBSD