We have zoned a san fabric switch in thie exact configuration on a 3494 tape library. system A and tape drives 1,2,3,4 in one zone, system B and tape drives 1,2,3,4 in the next zone, system C and tape drives 1,2,3,4 in the third, system D and tape drives 1, 2,3,4 in the fourth and finally system E and tape drives 1,2,3,4 in the fifth zone. It works really well. You cannot have multiple iSeries in the same zone but the tape drives are not an issue. If that does not work then you need to check the tape drive book to see if there is a setting for allowing multiple devices in a zone. Of that I am not sure.