Connecting to two sets of FC switches

A newly installed SC9000 came with both 16gb (dual port) and 8gb (quad port) FC HBA card. 16gb FC ports are connected to two brocade6510 switches (Fault Dom 1 & 2 virtual port mode).

There are two existing Brocade 300 switches connected to existing VNX storage and servers.

I created two additional fault domains with two 8gb ports from each sc9000 controller connected to brocade300s. This is also in virtual port mode.

After that, I created zones on brocade300 switches and mapped a volume to  two node citrix XenServer 6.5 cluster. XenServer GUI shows the new storage repo with multipath 2 of 2.

Now when I perform an offline copy of VM to this new repo, transfer rate is really slow ~24MB/sec. Is there anything I missed? Is there any issue using a single hba port to access LUNs from both vnz and compellent at the same time?