NFS+buildworld=silent reboot

I have a new (to me) box setup running current.  It is a Proliant 5500:
	4x550/100/1M
	1GB EDO
	Thunderlan 10/100
	Smart 3200? RAID controller
	7x9.1GB Cheetah (~54GB Raid 5)

It seems to work well, but if I try to do a 'make buildworld' over NFS
mounted /usr/src and /usr/obj it resets (NO PANIC). I tried building the
kernel with debug in it, and after an indeterminate amount of time into
the buildworld the machine resets (still NO PANIC). I am pretty sure I
remember something similar to this in the past but checked the mailing
lists and couldn't find it by guessing words :).

There are two things about this problem that bug me.  First, I do this
buildworld daily using a Proliant 5500 with Quad PPro 200MHz.  And second,
I rsync'd the entire /usr/src tree directly to the machine and did the
entire buildworld (-j6) without a hitch.  I am tenuously blaming NFS (or
maybe my own stupidity) at this point because the rsync uses networking
and the buildworld used all the memory and CPUs.

Okay, a third thing bugs me; I was gonna put gigE cards in this box and
use it as a SAN with some of my databases on it remotely mounted from my
database servers.  I figured with enough memory in it and fast enough
networking (and a BIG UPS) it would beat the pants off directly mounted
hard drives in the database machines.  Now I am concerned that the
database machines would just constantly reboot themselves.

I have swapped out processors, memory, memory cards, SCSI controllers,
network cards, even re-installed on an entirely different RAID group (the
original was using 36GB drives), and finally pulled out all the parts and
put them in a different 5500 case with a different mainboard, I/O card,
SCSI module, etc.  At this point I don't think I even have any of the
original parts left in the machine, but the darn things still resets if I
do a NFS mounted buildworld.

- brian

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