Put differently if you unplug one, the overall bandwidth does not drop to 12Gb/s etc. it will disconnect a single HBA port on a number of servers and force them to failover to the other path and FC-VC module.
It does not do any dynamic load balancing or anything like that – it is literally a physical port concentrator which is why it needs NPIV to pass through the WWNís from the physical blade HBAs.
What does that mean ?
Unplugging an FC cable from bay 3, port 4 will disconnect one of the HBA imageconnections to all of the blades in bays 4,8,10 and 14 and force the bladeís host OS to handle a failover to its secondary path via the FC-VC module in bay 4.
A key take away from this is that your blade hosts still need to run some kind of multi-pathing software, like MPIO or EMC PowerPath to handle the failover between paths – the FC-VC modules donít handle this for you.
See, easy isn’t it. Give me an IP connection any day, it much easier than this technical masterpiece – NOT.