Change to Round Robin via PowerCLI?

This may be in the wrong place and if it is, I'm sorry.

I'm trying to change all the Datastores on all hosts for a particular cluster to Round Robin, and I came across this PowerCLI script, but I use a lot of RDMs and I think this script will make the RDM LUNS round robin too and I cant have that happen

$input | ForEach-Object {
Connect-VIServer VCENTERSERVERNAME
foreach ($ESXhost in get-cluster "ENTER YOUR CLUSTER NAME HERE"| get-vmhost)
{
Get-VMHost $ESXhost |Get-ScsiLun -LunType "disk"|where {$_.MultipathPolicy -ne "RoundRobin"}| Set-ScsiLun -MultipathPolicy "RoundRobin"
}
}

Any thought?