strange SCSI problem

["David S. Zelinsky" <zelinsky@us.net>]

I need help or suggestions with the following problem.  I'm getting desparate!

(Maybe this would better be posted in one of the comp.os.linux newsgroups, but
since I don't understand what's happening, I can't rule out that it's somehow
Debian-specific.)

I have a Linux root partition on my (first) IDE drive; I also have an external
SCSI disk that I use for backup and testing.  The SCSI disk has two primary
partitions (sda1 and sda2).  Lately when I try to mount the first SCSI
partition (sda1), my machine freezes (requiring a hardware reset), sometimes
after reporting a segmentation fault and a message such as:

	Unable to handle kernel paging request at virtual address de2cd460

The second partition on the SCSI disk mounts without problems, and behaves
normally.

I can run fsck on the first partition, and it shows up clean (even with -f).

Moreover, I also have Linux installations on each of the two SCSI partitions,
and I'm able to boot normally from them both, and mount all of my Linux
filesystems, including /dev/sda1, without any trouble.

Can anyone explain what might be causing this behavior, and/or how to fix it?
Failing that, can anyone suggest how to go about diagnosing the problem?

Following are some more details.

SOME HISTORY:

This all began two days ago, when I tried to mount my Jaz disk (/dev/sdb), and
all hell broke loose.  I've since decided the Jaz disk must be defective,
since I can't access it from anywhere, including the SCSI adapter's BIOS.  But
I don't understand how relates to the problem with /dev/sda1.  Until two days
ago, everything had been working fine for months, including the Jaz disk and
the /dev/sda disk.

SYSTEM SPECIFICS:

  INTEL Pentium
  48 MB RAM
  64 MB swap partition
  SCSI adapter:  Adaptec AHA-2940
  External drive is a Quantum LPS340S (from LaCie).
  IDE drive has Debian 1.1 with Linux kernel 2.0.20 and also 2.0.0
  /dev/sda1 has Debian 1.1 with 2.0.0 kernel
  /dev/sda2 has Debian 1.3 with 2.0.29 kernel
  All partitions are less than 80% full.

THINGS I'VE TRIED:

  I ran fsck and repaired damage to /dev/hda3 (the Linux root partition on the
IDE drive) after each crash.

  I tried booting an old 2.0.0 kernel I have on the IDE drive, with the same
results.

  I re-installed the 2.0.20 kernel from a Debian package (that I had built
with kpkg last time I compiled the kernel).  Nothing changed.


Thanks in advance for any advice!


=-=-=-=-=-=-=-=-=-=-=
 David S. Zelinsky
  zelinsky@us.net
=-=-=-=-=-=-=-=-=-=-=


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