Hi David
Before you consider the virtualized part of the adaptor, you should consider the hardware connectivity.
Following configurations are possible (lets assume B200-M3)
1) VIC-1240 (MLOM) plus 2204 (IOM)
2) VIC-1240 (MLOM) plus 2208 (IOM)
3) VIC-1240 (MLOM) + Extender plus 2204 (IOM)
4) VIC-1240 (MLOM) + Extender plus 2208 (IOM)
the resulting bandwith (adpator - chassis backplane - IOM) are the following
1) dual 1 x 10G
2) dual 2 x 10G
3) dual 2 x 10G
4) dual 4 x 10G
If you now create n x vnics and m x vhba in your service profile, they are multiplexed over the available physical bandwith above; so you will have oversubscription !
Lets assume you have a ESXi server with 2 vnics, one connected to fabric a, the other to fabric b. Lets also assume you have configuration 2) or 3); then your vcenter shows a vnic of 20G
You control the oversubscription of the adaptor configuration; eventually, you could also create QoS policy and attach it to a vnic.