Do I need more SFP+ host ports if I add another PS6210X disk shelf

Hi all

We have a Server 2012 R2 4 node Hyper V cluster with each host having 2 10GbE SFP+ dedicated to iSCSI traffic. We need to expand the capacity of the SAN and our vendor has quoted for another shelf but is saying we need another 2 10GbE SFP+ ports in each of our hosts. Is this correct ?

I was under the impression that each of our hosts are already 'hooked' into the iSCSI fabric with MPIO active and therefore do not need any more physical iSCSI connections.

If we opt not to install extra iSCSI Nic's will we lose performance ?

many thanks

Gary