I noticed that one SCSI-Channel is missing.

That's the controller for the drive bay and other internal drives
with it's 2 channels:
siop0 at pci0 dev 3 function 0: Symbios Logic 53c875 (ultra-wide scsi)
siop0: using on-board RAM
siop0: interrupting at ipl 32
scsibus0 at siop0: 16 targets, 8 luns per target
siop1 at pci0 dev 3 function 1: Symbios Logic 53c875 (ultra-wide scsi)
siop1: using on-board RAM
siop1: interrupting at ipl 38

But there is another 53c875 with only one used channel for the external
SCSI connector.
Well there are no devices connected but the controller itself should be
probed.

-- 
B.Walter              COSMO-Project         http://www.cosmo-project.de
ticso@cicely.de         Usergroup           info@cosmo-project.de