stability problem with iir(4)

[Bjoern Koenig]

Hello,

there is an Asus PU-DLS mainboard and a Vortex ICP GDT8524RZ+ SCSI-RAID
controller card. After creating a RAID 5 with three Hitachi Ultrastar 146Z10
hard disk drives, I installed FreeBSD 4.9-RELEASE and it seems to be fine,
but after some minutes of doing something hard disk resp. RAID access fails.
No error message, everything simply stops working; system hangs. Kernel is
still active, because sending a ping to the 'dead' machine will cause a
response. If I use FreeBSD 5.2.1-RELEASE I got at least a message from
iir(4) that the hard disk doesn't respond, but it's the same problem. Using
another RAID type, e.g. 0, same happens. But using each disk as single, I
can benchmark the system for hours and hours without problem. There is also
absolutely no problem if I install Windows Server 2003 on RAID, so I suppose
it's not a hardware failure.

Does anybody have an idea what's going wrong?

Thanks for help
Bjoern Koenig