See my post on configuration and migration to multihop FCoE for details on my lab setup – https://jeremywaldrop.wordpress.com/2013/04/11/cisco-ucs-fcoe-multihop-configuration-and-migration/
When I first configured UCS multihop FCoE I experienced terrible SAN performance. It was so bad that it took 20 minutes to boot a single virtual machine.
Jeremy Waldrop's Blog 