Linux-kernel mailing list archive 1999-36,: Re: Adaptec 2920A & fdomain.o (again) (Bugzilla #4670)

# Re: Adaptec 2920A & fdomain.o (again) (Bugzilla #4670)

Rik Faith (faith@cs.unc.edu)
Tue, 7 Sep 1999 05:21:27 -0400 (EDT)

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On Mon 6 Sep 1999 15:57:26 -0400,
Chuck Mead <chuck@moongroup.com> wrote:
> banner:
> AHA Adaptec2920 BIOS Version 3.0 1994-1995
[...]
> scsi0: <fdomain> No BIOS; using scsi id 7
> scsi0: <fdomain> TMC-36C70 (PCI bus) chip at 0x6100 irq 10
> scsi0 : Future Domain 16-bit SCSI Driver Version 5.50
> scsi : 1 host.
>
> We have 3 of these cards with two of them in operation right now so I've got
> plenty to choose from for testing!

It is always good to try more than one card. And it sounds like you tried
more than one motherboard. Did you also try more than one disk drive? And
more than one SCSI cable? (E.g., vs. moving the drive and cable from one
machine to another? -- I can't tell if you're doing this or not.)

When I sent you private email about this a week ago, I suggested that the
kinds of problems you are seeing are typical of incorrect termination or a
bad device. Incorrect termination doesn't always make the SCSI bus fail
completely. Instead, incorrect termination can make the SCSI bus fail for
certain regions of the disk and/or under certain kinds of load. I think
this is what you are seeing, especially with the SCSI timeouts you
reported.

Since it sounds like you have two SCSI devices in your machine (the disk
drive and the SCSI controller), you should have each physical end of the
cable plugged into a device. If there are terminating resistor packs on
the devices, they should be plugged in. SCSI controllers often have
termination settings in BIOS, or do autodetection (which is often wrong, so
you should use a jumper or BIOS setting if available). Modern disk drives
often have jumpers for termination, and a separate jumper for "active
termination" or "termination power". You should have the SCSI controller
and _one_ disk drive provide termination power (drives often autodetect the
need for termination power (or autodetect when the proper jumper is in
place)). There should be nothing plugged into the external SCSI connector
on the card, and you should not use passive resistor packs plugged into the
end(s) of the SCSI cable.

I'm really sorry that I can't help more. On occasion, there are people who
report bugs like the ones you have reported. Most of the time, when those
people solve their problem, the problem is bad termination, a bad cable, or
a failing disk drive. The rest of the time, they get another controller,
and we never reach resolution of the problem. Since I can't duplicate
failures like this on my test system, I suggest you try another type of
SCSI controller. The Future Domain chipset is very old, and most modern
SCSI cards, even cheap ones, will have better performance than the one you
have now.

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