IBM x305 + etch + Adaptec AAR-1210SA : server locks up

["Chris ." <fracrist@gmail.com>]

Hi all,
I installed etch on 2 ibm x305 (cisco rebranded) with 2 sata drives
connected to a Adaptec AAR-1210SA controller. I set up the disks as
jbod and software raid through md.
I'm using the stock kernel that comes with etch, no unusual patches or
self compiled packages.

After some time that the machines are running they start to lock on
accessing disks.
The time between lock-ups is not always the same.
The server load is not always the same (problem occurs on heavy loaded
server and on light lodaed server).
I have nothing in logs (obviously, since disks stop working) and
nothing on the console.

I set the slow_down=1 parm in sata_sil module , passed the noapic and
acpi=off as kernel boot parameters (someone said that this solved
issues with random ibm x305 lockups) , but the problem still occurs.

Please let me know what kind of informations should I give to help
clarifying (and solving :-) the problem.

Thanks in advance,
Francesco.