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SubjectRe: ncr53c8xx SCSI driver locks up computer after timeout message
Gérard, thank you so much for writing back to me!

Thus spoke Gérard Roudier:
> > As the README for the ncr53c8xx suggests, I have configured the drive with:
> > - only asynchronous data transfers
> > - tagged commands disabled
> > - disconnections not allowed
>
> The README also suggests to first check that your SCSI bus is compliant to
> specs. Let me assume you did it. :)

I surely did. It's all brand new equipment, terminated properly (my older
problems were due to poor termination, which is now clearly fixed (I had
severe data loss before, and frequent. Now, things are very stable except
for this lock-up problem)).

> > Thus, I am not using any advanced features that might be buggy.
>
> IMO, mixing a JAZ device with a fine Fast-40 Hard disk on the same SCSI
> BUS is kind of suicide, since the JAZ devices are known to be crappily
> firmwared.

Hmmm... do you think this could be the root cause of my problem? Is it
worth using a spare older SCSI card of a different brand to handle the Jaz
drive separately?


FWIW, I have the Jaz on a separate chain (the card has multiple chains for
Ultra2, Ultra, and traditional SCSI-II). Also, the Jaz is unmounted when
the problem occurs.

The LVD/Ultra2/80MBsec drive is on a chain all by itself. One internal
cable from the card to the drive to the terminator.

> > Every once and a while, I get something like the following in my log files:

> You got 2 SCSI interrupts in the same second (UDC+PAR) that seem to have
> occurred for a single cause. This is not impossible if the device
> disconnected the BUS and the chip was reading the SCSI BUS, or if the
> disconnect had been too hard. Btw, we get such kinds of error conditions
> with not correctly set SCSI BUS.

I apologize, but I am not sure what you mean by this. Can you explain
further?

Specifically, what do you mean by 'device disconnecting the SCSI bus'. I
have disconnections "not allowed". Can it still happen anyway?

Also, what do you mean by "disconnect being to hard"?

Finally, what do you mean by a "not correctly set SCSI bus"? Do you mean,
set as in the card is not seated properly? Or, not set properly in the SCSI
BIOS parameters?

> I suggest you the following:

> 1 - Make sure that your SCSI BUS is, at least theorically, correctly
> configured (cables characteristics and quality, terminator positions,
> etc...). If you aren't sure enough, send me (us) the description of your
> SCSI BUS (cables length, position of each terminator and devices).

I have checked and rechecked this a number of times.

> 2 - If you donnot have either old 810 rev. < 16 or 815 or 825 rev < 16 on
> your system, give a try with the latest sym53c8xx-1.2a driver that has
> been recently enhanced for SCSI error recovery. Changes haven't yet been
> backported to stock ncr53c8xx driver.

Where do I get this?

> 3 - Send me the messages printed by the driver at bootup using driver
> verbose level 2. Boot command line : ncr53c8xx=verb:2

I will do this the next time I reboot the machine.

> 4 - Never use lspci command or cat /proc/pci/your_895_device under root
> account with linux-2.1/2.2 since the reading of config space bytes 128 to
> 256 will just read the whole IO register space of the chip and trigger
> bunches of side effects that have every chance to kill your system.

Hmm...Interesting. I will be sure not to do this.

--
Bradley M. Kuhn | bkuhn@ebb.org | http://www.ebb.org/bkuhn

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