FC SANs don't use an MTU so you don't need to take that into consideration. MTU and Jumbo Frames are Ethernet concepts. A Jumbo Frame is just frames that are greater than the conventional frames of 1500. As algreco81 said, it is better to have a higher MTU for performance reasons, but it is not a requirement for migrations to work. It only improves VM migrations (copying the running instance of a VM and its active RAM to from one host to another). The storage stays in place.