Ok, I've done some experiments:
- tried booting linux, I've not been able to load a kernel
  (boot dva0 is not enouth)
- The FreeBSD 4.0 snapshot will work if the scsi adapter (either compaq's
  dual-channel+ethernet of a standart 875 tekram) is on the primary PCI
  bus - it seems to have troubles with the DS20's pci-pci brige.
- NetBSD doesn't work either with the compaq or tekram scsi adapter,
  on the primary or secondary pci bus.
  But NetBSD works fine with a external drive attached to the tekram
  (can't connect it to compaq's adapter, I need a special cable :(

So my guess here is that our NCR driver doesn't work with the storageworks
devices, I'm not sure the reason. One strange thing is that I get these
messages:
probe(ncr1:0:x): extraneous data discarded.
probe(ncr1:0:x): COMMAND FAILED (9 80) @0xfffffe0000128c00.
only for 0 <= x <= 7. Targets 8 to 15 looks fine. I'll try moving the internal
disk to a higther target if possible (I'm not sure, I need to read the
docs first).
With more though these messages looks familiar, I think I've seen them on
my small alpha (I think it's a AXPpci33, it's really slow) when reboot it.
A poweroff/poweron usually fix the problem. I may also have seen them a couple
of time on a PC.

I think I'm going to look at this ncr driver a bit closer. Any pointers to
docs ?

--
Manuel Bouyer, LIP6, Universite Paris VI.           Manuel.Bouyer@lip6.fr
--