The supported configuration for the AX4 is failover mode 1 (active/passive) - there is no mode 4 (ALUA). When you use failover mode 1 and are running  ESX, EMC/VMware only support MRU on the hosts.  That said, RR might work. If you do use RR, you should look at the IO Operations Limit configuration setting - the default is 1000, you can get better performance using 1 - Google "IO  Operations Limit". Be aware that we can not support this configuration as it has not been qualified.  glen
Hello.  I have an AX4-5i dual SP array with a few vSphere 5 hosts connected using VMWare's native multipathing.  I dont have PowerPath/VE.  I was wondering if the AX4-5i performs better using round robin?  I have been using round robin for almost a year now, but I came across a forum post where someone mentioned it is not recommended on the AX4-5 because it is not ALUA supported.  I have each host setup using EMC's best practice, where port 1 on SPa is on one subnet, and port 2 is on another subnet.   Each VM has 4 paths available to the AX4-5i.  We have been having some performance problems on our SQL and Exchange servers so I am trying to make sure everything is setup correctly.  Thanks for your time.
VMWare iSCSI Round Robin support on AX4-5i array using NMP