System crashes under heavy disk i/o

[Erik Norgaard]

Hi:

I have had this problem for a while, both on 7.x and now with 8.0:

I have a:

FreeBSD 8.0-RELEASE-p1 #0: Fri Dec 11 11:53:19 CET 2009
     norgaard at localhost:/usr/local/obj/usr/local/src/sys/GENERIC
Timecounter "i8254" frequency 1193182 Hz quality 0
CPU: VIA Nehemiah (800.04-MHz 686-class CPU)
   Origin = "CentaurHauls"  Id = 0x69a  Stepping = 10
real memory  = 268435456 (256 MB)
avail memory = 231383040 (220 MB)
atapci0: <VIA 6420 SATA150 controller>
ad6: 476940MB <Seagate ST3500320NS SN04> at ata3-master SATA150

In normal operation I have no problem, but when performing intensive 
read or write for a prolonged time the system crashes. This happens also 
even if the partition is read-only. The crash occurs both with single 
large files (1GB) as well as many small files (10kb-10MB).

Currently, I'm backing up to an external drive over the network. I don't 
know if it's network related or disk related, but I guess it's disk 
related as I have no log of the failure. I don't know if it's the disk, 
contoller or something else. This is a headless machine, so I'm left 
guessing.

My two questions:

- is there any utility that I can use monitor the system to see what's 
going on, when or why?

- is there any way that I can slow down the disk i/o?

since the system works fine in normal operation, I hope that slowing 
down the disk operation would be a workaround, at least till I get my 
data onto the external drive.

Thanks, Erik

-- 
Erik Nørgaard
Ph: +34.666334818/+34.915211157                  http://www.locolomo.org