I have (2) TSM servers on AIX (H50 and H70) with 2GB FC adapter. I have
(15) 3590 and 6 (3580) tape drives hanging off a single adapter from each
server.  I'm sure in a lab somewhere that my single adapter could be shown
to be a bottleneck when trying to stream data to all those
drives...however in the real world that I happen to live in I rarely see
the an adapter pushing more than 130mb.  Not sure I would recommend this
as best practice, but I have no real complaints.
I will say that location of the adapters can make a significant difference
in the throughput. For instance, sharing a given bus with GigE, SSA, and
FC tape is going to introduce a bottleneck at the bus...just something to
keep in mind.  Some time ago I relocated the FC adapter to a different bus
and immediately saw 40% improvement in the throughput of the adapter.


David R. Nicholson