Unexplained problems and log messages

[Tom Wirschell]

Relevant hardware:
P3/733 w/ 256 MB RAM
Adaptec 2930U2 (ID0)
One bus holds (in the order as it appears on the SCSI chain):
	external HP ScanJet 5P (ID3) ASYNC 10MB/SEC
	internet Pioneer cdrom (ID2) SYNC 20MB/SEC
	internal Plextor cdwriter (ID4) SYNC 20MB/SEC
The other holds:
	internal Quantum harddisk LVD (ID1) SYNC 80MB/SEC

I recently updated the SCSI firmware to its latest revision (v2.20) and did
the same for the Plextor writer (1.07) but to no avail. The Plextor is
currently explicitly terminated and the scanner is supposed to see for
itself that it should be terminated and do so.

I'm running Linux kernel 2.2.17 right now, but know for a fact that this
problem was occurring with kernels as old as 2.2.12 and probably even
older.

Now everything works fine most of the time. The only exception is when I'm
scanning. At seemingly random intervals the scanning stops and a line is
printed in the messages file saying:

kernel: (scsi0:0:3:-1) Unexpected busfree, LASTPHASE = 0x1, SEQADDR = 0x161

This will typically pause the scanning process for a few annoying seconds,
but no real harm done. Every so often however, this problem will result in
a lockup of the SCSI bus, which will, after 60 seconds, reset itself and
hopefully continue as if nothing happened.
At some rare occasions however the bus reset isn't sufficient and a hard
reboot is my only recourse.
This problem also occurred when I was using a BusLogic FlashPoint LT
adapter but I don't know about the log messages. It's been a few years
already.

Once these errors start to pop up, the other devices on the SCSI chain
begin giving problems. CDWriting fails with strange errors and such. The
quick solution here is to simply mount a CD. It will trigger a reset of the
SCSI bus and things for the most part return to normal until the errors
start to pop up again.

What I was hoping for is that the people on this list are able to tell me
just what the above log entry means. Cable problem? Termination problem? I
really don't know and attempts to find out have failed miserably.

I don't know if it matters, but I'm running the distributed.net client
program so the CPU load on my machine is always 1.0

Any insights will be highly appreciated.

Sincerely,

Tom Wirschell
-- 
I got on the internet once. Ten hours of every sexual
perversion you ever imagined, and the Hamster Dance.
Greatest ten hours of my goddamn life.
	- Captain Joe Siry, Witchblade 43 -



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