So we just put a couple of Netapp SAN's in our environment, and I've noticed after the installation tech left that we're getting Partner Path errors, which seems to indicate that my ESX Servers are going over the path to the incorrect controller, then going through the communication link between the controllers to get to the proper set of disks. Basically what I think happened was we created the LUN's, moved VM's, then tested failover of the Netapp Controllers. On the ESX side, my Fibre settings are set to "Most Recently Used", so the server never went back to the original path it was using.
I've seen on the full version of ESX, you can install a Netapp tool to ensure the multipathing is done properly, but is there anything I can do with ESXi rather than always having to change the path? Also, this gets really hard to manage when you have multiple LUNs, and its very hard to identify which Servers/LUNs are going through the wrong path.
Also, I'm running clustered 3140 Controllers, and running ESX4i Update 1 on the VMWare side. I'm basically just looking what my fibre settings should be on ESX, and how to easily manage these misconfigurations.
Alternatively to installing NetApp tools, you can enable ALUA on your igroups and change vSphere's multipathing to "Round Robin (VMware)" for each datastore on each host. Just remember to change this setting for all hosts each time you add a new disk.