I recently bought another SCSI disk to put on my 340.  I then looked at the
scsi disks I was having problems getting recognized.  Seems that whether
the disk spins up automagically or needs the adapter to tell it to determines
whether the kernel will probe it correctly.  

Point of information only, since I'll probably not tear the system back down
to lookup the exact error message, or to play with it.  

(I currently have a micrapolis 1.6G, seagate 330, (both 5.25 FH) a conner 40M
(3.5 slimline) all sitting on an old pc power supply as my system disks)