ESX 5, iSCSI and VMWARE - Logical Drive Not On Preferred Path

Morning \ Afternoon All,
I am having a nightmare with a DS3524 and am in desperate need of some help.

 

We have a DS3524 with x2 1GB Ethernet Dual controllers (x4 1GB Nics per controller), we are having issues with it giving an error:

 

Logical Drive Not On Preferred Path

 

Setup:

 

We have created multiple array with separate logical drives within:

 

Array 1: RAID 5 - x2 Logical Drives - Preferred Path ContA
Array 2: RAID 5 - x2 Logical Drives - Preferred Path ContB
Array 3: RAID 1 - x2 Logical Drives - Preferred Path ContA
Array 4: RAID 5 - x2 Logical Drives - Preferred Path ContB

 

Once we receive the error the controller ownership for all Logical Drives are on controller A, Once we swap them back over they failover again within 15 minutes.

 

Connected to the SAN are x5 ESX hosts, no other servers are connected. The ESX Hosts use the iSCSI Software initiator to connect.

 

The network setup is as follows:

 

Controller A:
Port 3: 10.10.15.11
Port 4: 10.10.16.11
Port 5: 10.10.15.12
Port 6: 10.10.16.12

 

Controller B:
Port 3: 10.10.15.13
Port 4: 10.10.16.13
Port 5: 10.10.15.14
Port 6: 10.10.16.14

 

We have x2 switches one configured with vlan 2 and the other vlan 3 - all 10.10.15.x is within VLAN 3 and 10.10.16.x is on VLAN 2
The ESX Host has been configured with x2 NIC that have be bound to the ISCSI initiator - x2 VMKernels - 1 interface live for the 15 range and another for the 16 range

 

Each ESX box is able to ping all interfaces on the DS3524

 

Each presented LUN has been configured to use Round Robin Load Balancing - I understand this is supported from the following link:

 

http://www-304.ibm.com/support/docview.wss?rs=591&uid=ssg1S1003554

 

Looking at the VMware HCL Round Robin is unsupported

 

http://partnerweb.vmware.com/comp_guide2/detail.php?deviceCategory=san&productid=14700&releaseid=76&deviceCategory=san&partner=43&releases=76&arrayTypes=1&isSVA=1&page=1&display_interval=10&sortColumn=Partner&sortOrder=Asc

 

Can anyone point out any configuration issues that may cause this issue?
Thanks
Tim