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Date: Tue, 12 Mar 1996 02:26:17 -0700 (MST)
From: Alan T Krantz <atk@alumni.cs.colorado.edu>
Message-Id: <199603120926.CAA06253@alumni.cs.colorado.edu>
To: joerg_wunsch@uriah.heep.sax.de, rgrimes@GndRsh.aac.dev.com
Subject: Re: Slow Toshiba 6.7X cdrom drive.
Cc: fcawth@jjarray.umd.edu, freebsd-hardware@freebsd.org,
        freebsd-scsi@freebsd.org
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  ||From owner-freebsd-scsi@freefall.freebsd.org Mon Mar 11 22:06:52 1996

  ||> 
  ||> 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

Out of curiosity I tried this (P-100, NCR810 with FreeBSD 2.0 ) and got
300mb with 4092 and 615mb with 8192 for a Toshiba XM-3601TA 0725. (512
and 1024 were illegal block sizes). Also got around 4 megabyte for a
Fuji M1606S-512 which seems a little high...

atk