If I understand what you are asking for there is actually a way of checking this, its not entirely straight forward but its not too hard and its low risk. The trick is to set a throttle on the igroup of that server and then monitor the FC ports on the controller.
1. set a throttle on a server
2. use the server whilst monitoring the fc ports
3. unset the throttle
igroup set igroup_name throttle_reserve 1 igroup set igroup_name throttle_borrow yes
2. igroup show -t -i 5 -c 12 > you ll see a line specifically for the igroup that you set. This syntax is for 60 seconds with updates every 5 seconds.
Use the server in question, perform some writes/reads etc.
igroup set igroup_name throttle_reserve 0
try using the command (igroup show -t -i 5 -c 12) before you set the throttle to get an idea of what it does before setting it. once its set to an igroup
you ll get to see what port the server is using.
You can also find this out on the server by using ESX host utilities, ESX host utils. is a must on the server, so it should be there.