2940UW problems.

[James O'Kane]

I hope this list is for linux and freebsd and that I'm not asking the
wrong people. CC me on any related reply as I'm not currently subscribed.

It seems that we have been having trouble with a 2940UW card with linux,
and it is our best guess that it is being sent too many requests and one
is being dropped by someone, the drivers get confused and reset the bus
and start over again. The errors that we get are similar to the following,
but we would have these errors on 3 different 2940 cards, 3 different
machines, 3 different classes of machines, PPro, PII, P200.

---error----
Jun 16 18:07:08 server9 kernel: (scsi1:0:2:-1) Unexpected busfree,
LASTPHASE = 0
xa0, SEQADDR = 0x155
Jun 16 18:07:08 server9 kernel: (scsi1:0:2:0) No active SCB for
reconnecting tar
get - Issuing BUS DEVICE RESET.
Jun 16 18:07:08 server9 kernel: (scsi1:0:2:0)       SAVED_TCL=0x20,
ARG_1=0xff, 
SEQADDR=0xfc
Jun 16 18:07:12 server9 kernel: (scsi1:0:2:0) Synchronous at 40.0
Mbyte/sec, off
set 8.
Jun 16 18:07:12 server9 kernel: (scsi1:0:4:0) Synchronous at 40.0
Mbyte/sec, off
set 8.
Jun 16 18:07:12 server9 kernel: (scsi1:0:3:0) Synchronous at 40.0
Mbyte/sec, off
set 8.
Jun 16 18:07:13 server9 kernel: (scsi1:0:5:0) Synchronous at 40.0
Mbyte/sec, off
set 8.
---end error---


There are also often time a SCSI abort and timeout while resetting the
bus, but those didn't make it into the error logs. In doing some searches
on www.deja.com I noticed that some people suggested putting no_reset in
the lilo config, but that doesn't seem to be a solution the way it's
presented, it only seems to hide the symptoms.

While looking at /proc/scsi/aic7xxx/1 we noticed that it contained this
line:                    SCBs: Active 0, Max Active 4,


I don't claim to totally understand SCB's, but our theory is that our
software (raid 5) is producing more SCB's than the drivers are setup for
and one is getting lost by someone. Is there a reason that the max active
is 4? This chain has 5 drives on it. Is it safe to increase the SCB max
value or are we guessing wrong at the problem?
thanks
-james


James O'Kane -- Linux Administrator     |If only /usr/sbin/sendmail
Justsystem Pittsburgh Research Center   |could do your taxes...
4616 Henry Street                       |
Pittsburgh, PA 15213                    |
(412) 683-4095                          |




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