This is one of those one liners I think that I’ll never use again, but once again, I found myself using it to fix MPIO policies on a vSphere 5.0 environment plugging into a Nexsan storage array.  I’ve previously used it on EMC and LeftHand when the default MPIO policy for the array type at the time of ESXi installation is not the recommended one after the fact, or in the case of LeftHand, it is wrong from the get go.

get-vmhost | get-scsilun | where vendor -eq "NEXSAN" | set-scsilun  -MultipathPolicy "RoundRobin"

In this case, it was over 300 LUN objects (LUNs x hosts accessing them), so that’s about 5 mouse clicks per object to fix via GUI.  Translation, you REALLY want to use some kind of scripting to do this, and PowerCLI can do it in one line.

You gotta love PowerShell!