[2610] in linux-scsi channel archive
Re: Termination problems ?
daemon@ATHENA.MIT.EDU (Daniel M. Eischen)
Sat Oct 11 14:14:04 1997
Date: Sat, 11 Oct 1997 13:11:45 -0500 (CDT)
From: "Daniel M. Eischen" <deischen@iworks.InterWorks.org>
To: beer@mrbounce.compsoc.man.ac.uk
Cc: Zlatko.Calusic@CARNet.hr, linux-scsi@vger.rutgers.edu
> I have a SCSI-II CD recorder (Philips CDD2600) and a Quantum Atlas II UW
> on an Adaptech 2940 UW controller. While the disk works very fast and
> without any problem at all I have great problems with the CD. When I try
> to play an audio-cd, the cd responds with some kind of sense-error. Then
> the whole system locks-up the SCSIbus gets reset and after aproximately
> 30 sec the cd starts to play normaly and everything works fine. The same
> thing hapens when I try to stop the cd, playing. Here's a snapshot of my
> log file:
What was the sense error? Note that the driver doesn't handle sense
errors; it passes them back up to the mid-level SCSI code and the
target drivers.
> Also when I burn a blank CD everything works fine until "cdwrite v2.0"
> comes to the end phase of "fixating" the CD, then I get similar errors.
> I have tested the CD drive with many data-cds and there was no problem. I
> read in the SCSI-HOWTO that sense errors can occur when driving the
> SCSIbus at high speeds (ULTRA) and provide pure termination. My SCSI chain
> is like this:
>
> ID 7 6 5 4 3 2 1 0
> Device Adaptech Quantum Philips
> UW CNTRL UW HDD CD rec.
>
> I have terminated the CD rec. and I removed the termination of the HDD.
> The controller automatically sets its termination.
And you have a properly terminated 68-pin to 50-pin adapter
on the Quantum (the Quantum and the CD recorder are on the
same 50-pin bus, right?)?
Don't use your CD recorder to terminate the SCSI bus. It most
likely doesn't use active termination. The Quantum will, AFIAK,
use active termination, so use that to terminate the bus.
Also, don't rely on the driver to do the right thing when
auto-termination is enabled. The Adaptec documentation I have
doesn't give enough information about this. Use manual termination
(for your setup, with everything on the internal narrow bus,
use High On, Low On)
> I use linux v2.0.30 on an AMD K5 100PR with 32MB sdram.
Upgrade to 2.0.30-pre10+ or 2.1.42+ to get the latest aic7xxx
driver. There were many bug fixes.
Dan Eischen
deischen@iworks.InterWorks.org
