SCSI cabling on Base module & TL891

[Ayman Altounji]

Running NT4 sp6a, ArcServe 6.61 sp1 or ArcServe 2000 sp2.
TL891dlx with 2 40/80 tape drives SCSI ID 1,2
Expansion unit - DLX base unit. SCSI ID0
Server is a Proliant 1600 with a Compaq 64bit/66 mhz dual channel wide ultra3 scsi adapter.

When I connect the SCSI cable to the Expansion unit then daisy chain it to the first tape drive on the 891 and then daisy chain that one to the second tape drive and then terminate it as per documentation the system will not run. ArcServe comes up with all sorts of scsi errors.

If I connect one channel of the scsi to the expansion unit and terminate. Then connect the second channel to the tape drive 1 then daisy chain to tape drive 2 and terminate it all works fine.

Why does the first option not work. The reason I am asking is that I want to put a tape drive on each scsi channel as opposed to putting them both on the same channel and the robotics on the other.