Hangs with Adaptec 29320

[Andrea Venturoli]

Hello.
I've got two different servers running FreeBSD 6.1 and hanging:
_ one is a Dual Core Opteron running amd64 and experienced frequent 
hangs until I decided to turn off SMP;
_ the other one was an old Athlon XP working flawlessly with 5.x/i386; I 
upgraded to 6.1/i386 and started seeing sporadic hangs; I had an 
hardware upgrade to an Athlon64 x2 and decided to turn SMP on, but then 
the system wouldn't last half a day. I turned SMP back off again and the 
system is more or less working.

I don't get any core dump (altough I configured it properly) and DDB 
does not work. The only way out of this is hard resetting.

What this machines have in common is a RAID-1 gmirror setup on an 
Adaptec 29320 controller: one is PCI, the other on the MB (Acer Altos 
server), but both are obvioulsy driven by the ahd driver.
So my *guess* is that the problem might be related to this.

What I'm looking for is any help in solving or at least diagnosing this. 
Any tool, thread pointer, document or suggestion is appreciated.
(I would obviously love to be able to turn SMP back on).

  bye & Thanks
	av.