We have STL2 boards with the aic7899 on board.  They work fine under NetBSD 
1.6.1 with one drive as follows:

sd0 at scsibus0 target 6 lun 0: <IBM, IC35L018UWD210-0, S5BS> SCSI3 0/direct 
fixed

When we add a second drive the system halts with disk errors showing on the 
screen.  The second drive is a Seagate Cheetah Ultra320 ST336607LW.  The odd 
thing is that the second drive doesn't get trashed, the first one does.  We 
have tried this in a number of systems and have replaced both the original 
drive and the Cheetah.  Removing the drive allows the system to run forever.

This doesn't seem to happen with other drives.  This has been very frustrating 
for us.  Does anyone have any idea where we can start investigating this?  It 
seems like it must be a controller issue except for the fact that it works 
fine with other drives.
 
-- 
D'Arcy J.M. Cain <darcy@netbsd.org>
http://www.NetBSD.org/