fxp0: device timeout | SCB already complete.

[Palle Girgensohn]

Hi!

When I run network backups, one of our FreeBSD machines (backup client) get 
NIC timeouts and warnings from the scsi driver:

Jun  3 14:50:12 melon /kernel: fxp0: device timeout
Jun  3 14:50:36 melon /kernel: fxp0: device timeout
Jun  3 14:51:03 melon /kernel: fxp0: device timeout
Jun  3 14:51:38 melon /kernel: fxp0: device timeout
Jun  3 14:52:41 melon /kernel: ahc0: Timedout SCB already complete. 
Interrupts may not be functioning.
Jun  3 14:53:12 melon /kernel: fxp0: device timeout

Both machines are on a hubbed 100 Mbit/s half duplex network. Looking at 
the traffic with netstat -d 1, I see that as soon as the traffic increases, 
there is a timeout and traffic stops, after with the net is reachable 
again. This goes on and on. It only happens when there is much traffic on 
both NIC and SCSI, it seems (alas when running backups...)

Since there was a second NIC, it tried connecting it to the server using 
that NIC through a switch, on a private network, but then the machine 
nearly crashed, or at least came to a grinding halt. It seems, as soon as I 
pulled the ethernet cable it came back. This happened without any backup 
running...

To me, this sounds like some odd interrupt problem? It is a PCI machine 
with an Intel ?x440 (if memory serves me right) and dual CPUs 400 Mhz, 
running freebsd-4.7p2.

Any ideas where to look, how to debug or what to do?

Thanks
Palle