When comparing the 1:4 & 2:8 configurations, what is the role of the 2:8’s additional FICON channel?
The 2nd FICON port is not so much for accommodating through-put as it is for redundancy, considering that all the traffic from 8 ESCON ports could in most cases be driven by a single 2 Gb FICON channel, not to mention a 4 or 8 Gb channel. So, the primary reason for the second FICON port on a 2:8 Prizm is path redundancy. However, for controllers with two ESCON interfaces, two 1:4 Prizm units can be used to not only achieve path redundancy, but also Prizm redundancy.