I wrote up this blog entry and then deleted the whole entry while editing a typo. It seems to be a glitch in the developerworks Blog interface, but it could also be a code 16(problem lies 16 inches in front of keyboard). Anyway....
Cisco have filled a gap in the product line with their new MDS9148. IBM have offered the 4 Gbps capable MDS9124 24 ports) and MDS9134 (32 ports plus 2 x 10 Gbps ports) for some time. However for clients who were looking for a future proofed (read 8 Gbps capable) and scalable (read - offers at least 40 ports ala SAN40B-4) then clients were pushed up the the MDS9222i.
The MDS9148 ticks all the right boxes. It starts at 16 ports and scales up to 48 ports by concurrently activating 8 ports at a time. More importantly there are 8 Gbps of dedicated bandwidth for each port and 128 buffer credits for every group of 4 ports. You can allocate up to 125 buffer credits to a single port which is great if you have a distance solution using WDM technology. Finally the box offers all the usual Cisco functions including hot code activation (which is very important too).
If there is a downside, port densities are getting so high, that swapping out a single switch is becoming far more work. Having said that, we are now offering 64 port blades for the SAN768B and SAN384B which is great from a port density perspective, but means even more cables converging into the same real estate.