System hangs with unrecoverable SCSI bus or device hang.

[Hansel Kwok]

Hi,

I have a problem relating to my Cyrix 6x86 200+ and
Adaptec 2940 SCSI adaptor.

System Config:
	Cyrix 686 P200+ 
	AHA 2940 SCSI Adaptor
	48M RAM
	Segate 2GB SCSI Harddisk (scsi id 0)
	SCSI CDROM (scsi id 1)

Linux apache.gih.co.uk 2.0.20 #8 Tue Jul 8 00:02:31 BST 1997 i486

Problem:

	When there is heavy access to my scsi disk, 
the system hangs with the following messages. 

----
aborting command due to time out (pid 1126) scsi0 
channel 0 id0 lun0  0x28 00 00 2a 2b d6 00 00 72 00
(abort) Aborting scb0 TCL 0/0/0
-----

Then the system tries to reset the scsi bus. This
is what it thinks...

---
SCSI host 0 abort (pid 1126) timed out resetting
SCSI bus is being reset for host 0 channel 0 

aic7xxxx reset target/channel 0/
0 abort reset scb state 01 Data-In Phase SCSISIGI 0x44

abort scb asserted ATW - host device reset in message buffer.
---

System tried to repeat the reset but with the same results.
Then came the following:

---
SCSI host 0 reset timed out again
probably an unrecoverable SCSI bus or device hang.
---

This problem appeared during fsck when the filesystem
is unclean. It also appeared when X starts, or some
other disk intensive application.

Because it is a 6x86 200+, the bus clock is set to 75MHz.
When I set the bus clock to that of a 166+, which is
66MHz, the system is fine. I was able to use the system
for a long time without problems.

When the system hangs, the red led on the scsi card is
on constantly. I tried to see if the same problem appeared 
with NT, well, it did hang for a while with the red LED on, 
however, NT seems to be able to get out of it. However,
I was not able to do a lot of testing with NT.

Can someone tell me what the problem might be? 

Thank you.

Hansel.

-- 
Hansel Kwok.                                 Telephone: +44 (0)171 5946309     
Digi. Comms. Section, EEED                       Email: h.kwok at ic.ac.uk
Imperial College of Science,                          : hansel at gih.com
Technology and Medicine, London.                      : hansel at gih.co.uk