[tlug] freeze on AMD64 Dual Opteron server

[Evan Monroig <evan.monroig@example.com>]

Dear Tlug,

I have a server with two AMD64 Opteron processors and 8GB of ram, that I
use as a simulation box here at the laboratory.  Communitation with it
is entirely through ssh.

I have run simulations full time for a few days, generating tens of
gigabytes of data at high speed, all without problem.

But now I would like to send the data to another computer using rsync,
and after about 20 seconds it invariably hangs.

There is no way to do anything.  The ssh connection is cut, the computer
is doesn't appear on the network (I configured a static IP address).
I tried connecting a screen and keyboard to it while doing the rsync,
but after failure the computer is completely hung.  Frozen screen,
keyboard not responding (numlock, capslock..).

I think that it might be a kernel panic, and looked at /var/log/syslog,
/var/log/messages and others, and couldn't find anything related.

Here is some info about the system

dmesg: http://obakechan.net/e7Rj5pWm0N/dmesg
/proc/cpuinfo: http://obakechan.net/e7Rj5pWm0N/cpuinfo

uname -a
Linux sim2 2.6.15-27-amd64-generic #1 SMP PREEMPT Sat Sep 16 01:50:50 UTC 2006 x86_64 GNU/Linux

The kernel is a stock kernel that comes with ubuntu dapper.

Do you have any suggestion as to how to investigate the problem?

Thanks in advance,

Evan