Ok, finally sorted. Both hosts performing as they should. A combination of things. Updating vmware to use the Broadcom 2.2.1l.v50.1 driver then set up port binding as per latest Dell MD3200i deployment guide for ESXi 5 does indeed work. The signed VMWare driver for the Broadcom does not work for me so if anyone else has this issue, this was my fix. IOMeter reporting squential reads of 400MB/s when run at the same time on two hosts accessing separate disk groups through individual controllers in active/active scenario.  Thanks Jonathan
Hi,  We have an MD3200i loaded with 12 x 600GB 15k SAS drives. Two Raid 10 arrays with 4 LUNs per array. Using 2 x R710 servers with 4 NICs per server for iSCSI traffic using different subnet on each port - Server1 192.168.130.1 192.168.131.1 192.168.132.1 192.168.133.1 Server2 192.168.130.2 192.168.131.2 192.168.132.2 192.168.133.2 MD3200i Controller1 192.168.130.101 192.168.131.101 192.168.132.101 192.168.133.101 MD3200 Controller2 192.168.130.102 192.168.131.102 192.168.132.102 192.168.133.102 We have 2 switches for redundancy with the correct connections made. All LUNS are available, 16 paths per NIC, 8 active i/o, 8 standby, round robin enabled and showing 8 paths per LUN so all appears fine. When using ATTO benchmark, the read performance is crippled from 64k upwards whereas write shows up to 250MB/s. Having read many threads with similar issues, I have yet to find a fix. Delayed ack is disabled, we have tried Dell's old recommended way of a single vSwitch with all NIC's in active inactive configuration as per their best practices (confirmed correct by Dell engineer a while ago). I now have their ESXi 5 guide for MD3200i which recommends single vSwitch per NIC but then goes on to say add each NIC to the iSCSI initiater through VMKernel port bindings but they don't appear unless I put them in the same vSwitch.  [IMAGE]  Any assistance would be greatly appreciated.  Many thanks  Jonathan
MD3200i with ESXi 5 crippling read performance