Senjak,
It looks like "Get-NcVolFootptint" is the commandlet that returns this data. You can store all the footprint data for a vserver with the following command:
$Footprint = Get-NcVolFootprint -Vserver $vServerName
You can then look at the footprint data for each volume with $Footprint.VolumeBlocksFootprint[index]
Hope that helps,
Mike