$VC=" "
$UserName=" "
$Password=" "
$DataCenterName = ""
$ClusterName=" "


Function ResetAllLUN2RoundRobin
{
      # Connect to the VCenter server
      Write-Progress “Gathering Information” “Connecting to Virtual Center” -Id 0
      Connect-VIServer –Server $VC –Protocol https –User $UserName –Password $Password

      $esxservers = get-cluster "$ClusterName" | get-vmhost 
      foreach ($h in $esxservers)
      { 
            ##$h = get-vmhost $esxserver
      Write-Progress “Changing…” “Multipathing to Round Robin” -Id 0

            $hostView = get-view $h.id
            $policy = new-object VMware.Vim.HostMultipathInfoLogicalUnitPolicy
            $policy.policy = “rr”
            $storageSystem = get-view $hostView.ConfigManager.StorageSystem
            $storageSystem.StorageDeviceInfo.MultipathInfo.lun |
            where { $_.Path.length -gt 1 } |
            foreach { $storageSystem.SetMultipathLunPolicy($_.ID, $policy) }
      }
}

ResetAllLUN2RoundRobin