2940UW lockups, pls help

[Brian Ristuccia]

On Mon, 13 Jul 1998, Wes Brown wrote:

> 
>   I am running redHat 5.1 (kernel 2.0.34) on an alpha.  I am using a
> 2940UW scsi controller.  I have 3 scsi disks and one scsi cdrom drive
> inside the computer, I also have another 4 hard drives and one tape
> drive connected externally to the controller.  The problem is that when
> the computer tries to access more than one disk at the same time the
> computer hangs.  I am in a real bind here, trying to convince the powers
> that be that this linux (especially on an alpha) is a good solution, but
> this is making the machine too unstable.  What version of the aic7xxx
> driver should I be using, or is this a current problem.  If so can i
> partially disable the card to prevent it from sending more than one
> command at a time.   Can anyone give me some suggestions here?  I would
> very much appreciate it.
> 

I am using 5.0.18 on my SMP Intel box with good results. When I had
problems with heavy SCSI activity locking up the SCSI subsystem, it turned
out that bad termination was causing SCSI resets that would hold up the
machine forever. 

Make sure your host adaptor termination is _off_ if you have devices
connected to both ends of your chain. Make sure you have a wide device as
the last item on your internal chain, and that its termination is enabled.
If you have only narrow devices on your internal chain, keep termination
off, and install it as the second-to-last device on the chain. Put a
wide active termination pack in the last socket on your cable.

For the external devices, if you're using one of those 68->50 cables, it's
probably not terminating your high bits correctly. You need an adaptor
that terminates the high 8 bits and allows the standard non-wide 50 pins
to continue. 

If you are using a mix of wide and narrow external devices, you need to
put your wide devices first. Then put the 68->50 terminator, and finish up
with your narrow devices and a good active terminator at the end of the
chain. 

If you have any terminators without lights, or that are not labeled
ACTIVE, toss them out and replace them with active terminators. Toss any
skinny/old cables, or save them for use on a machine with a more tolerant
SCSI subsystem (ie, a mac). I know this should be obvious, but don't use
50 or 68-pin ribbon cables externally. 

Also, if you have disconnect or tagged-queue enabled on a device that
doesn't support it, you'll have these sorts of problems. 

--
Brian Ristuccia
brianr at osiris.ml.org
bristucc at baynetworks.com
bristucc at cs.uml.edu


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