I was never really happy with the performance I was getting on the Readynas 4200 about 95 MBs read. It was OK but not great for having multiple nics. So I finally did some optimization this weekend.
The trick was to turn off teaming on the Readynas and have each NIC on a separate Vlan. Then setup ESXi for MPIO round robin in the GUI with 4 NICs on separate Vlans. You would think this is enough but it is not. I was still getting 95MBs performance but instead of seeing 1 nic 100% utilized I saw 4 NIC's 25% utilized. This had me stumped till I found an article about MPIO round robin IOPS and how by default it is set to 1000. It needs to be set to 1. So this ESXi 5 command must be run on each host from SSH.
for i in `ls /vmfs/devices/disks/ | grep naa.600` ;
do esxcli storage nmp psp roundrobin deviceconfig set -d $i --iops 1 --type iops;done
Once I did that my read performance went from 95MBs to 400MBs with 4 NICs using the vmware OpenPerformanceTest.icf on IoMeter.
Now I am thrilled with the performance of the Readynas 4200 and feel comfortable virtualizing my Exchange server.
A detailed step by step guide has been posted here https://sites.google.com/site/abraindump/readynas-vmware-iscsi-performance
Troy
