Powershell Netapp - Total Volume size using get-navol

Purpose:
I needed a way to query a netapp filer to give all the volumes and their total size with snapshot reserve.This is my second powershell script so be easy on me :-) Also this requires dataontap powershell toolkit

              
param([string]$NetAppHost, [string]$username)

Import-module DataOnTap

$PathtoCSV = "C:\NetappTotalVolume.csv"

If ($NetAPPHost){$strNetAPPHost = $NetAPPHost}
ELSE{$strNetAPPHost = Read-Host "What is the Netapp hostname/IP?"}
If (!$strNetAPPHost){Write-Host "Error: Netapp hostname/ip not entered";exit}


If ($username){$strusername = $username}
ELSE{$strusername = Read-Host "What username?"}
If (!$strusername){Write-Host "Error: Username not entered";exit}

Connect-NAController $strNetAPPHost –cred $strusername

$allvolumesnames = get-navol | Select-Object Name,Available,TotalSize,snapshotpercentreserved

#set headers of CSV file
"Hostname,Available Space(GB),Used Space(GB),Total Volume Space(GB)" > $PathtoCSV
foreach ($netapp_vol in $allvolumesnames) {

$CurrentVolname = $netapp_vol.name
$VolumeSizeTotal = [math]::Round([decimal]((($netapp_vol.snapshotpercentreserved * 100) * $netapp_vol.TotalSize) + $netapp_vol.TotalSize)/1gb,2)
$VolumesAvailable =  [math]::Round([decimal]$netapp_vol.available/1gb,2)

#Create/add to CSV file
$Combine = $CurrentVolname,$VolumeAvailable1GB,$VolumeUsedSpace1GB,$VolumeSizeTotal1GB
$Combine -join "," >> $PathtoCSV
                 
    }