Date: Mon, 22 Jul 1996 14:02:19 -0700 (PDT) From: "Rodney W. Grimes" <rgrimes@GndRsh.aac.dev.com> To: amir@neuron.net (Amir Y. Rosenblatt) Cc: amir@neuron.net, freebsd-current@freebsd.org Subject: Re: SCSI errors and repeated panics Message-ID: <199607222102.OAA19362@GndRsh.aac.dev.com> In-Reply-To: <199607222049.QAA00424@prozac.neuron.net> from "Amir Y. Rosenblatt" at "Jul 22, 96 04:49:49 pm"
next in thread | previous in thread | raw e-mail | index | archive | help
> > I see justin replied about a kernel bug, but thought I might mention that
> > you did not complete the scsi bus termination description:
>
> OK -- I re-supped last night and recompiled my kernel.
>
> > The upper 8 bits are terminated on the 2940UW, if not you have
> > a miss termination on the data<7-15> signals of the scsi bus,
> > please check your SCSI-Select BIOS settings.
>
> I'm not entirely sure what you mean.
I mean that if you go into the SCSI-Select BIOS (Hit ^A during system Power
On Self Test (POST) when the Adaptec bios mentions it) and check the settings
of the on board scsi termination. You will find 3 or 4 options:
a) Automatic (I recommend against this setting, the detection logic
may fail under certain conditions.)
b) High/Low Enabled (ie, all 16 bits of the scsi bus are terminated.
c) High Enabled (ie, the upper 8 bits of the scsi bus are terminated)
d) Disabled.
In your configuration it _must_ be set to c) above... see the diagrams
in the Adaptec manual....
> I've had devices on boith the 8 and
> 16 bit internal connectors on the card since the first day I brought the
> machine online back in February. The only change I've made to the setup
> is that originally, the 4 gig HP C1533 DAT was at the end of the 8-bit
> chain and now it's in the middle, with the NEC CD-ROM drive at the end
> (the termination on both set appropriately as far as I could tell from
> the manuals).
Humm... I suspect that the HP C1533 DAT drive has active terminators,
ie the resistor value will be 110 ohms, and the NEC CD-ROM is using
passive termination, ie the resitor value will be 220/330 ohm. I highly
recommend (and the SCSI-II spec just recommends) that you use active
termination with Fast SCSI-II.
> From the outset I'd adjusted the 2940UW's built-in
> termination to match this configuration as specified in the manual.
> Furthur advice or clarification would be greatly appreciated, as it
> started giving me the same errors again a short while ago (I called the
> guy who was sitting at the console and had him bring prozac [the machine]
> down for 15 minutes rather than letting it panic and crash). Thanks in
> advance,
>
> -Amir
--
Rod Grimes rgrimes@gndrsh.aac.dev.com
Accurate Automation Company Reliable computers for FreeBSD
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?199607222102.OAA19362>