Advanced Sensor will Report vCenter Statistics about Resource usage.

PRTG-vCenter.ps1

<#
  .SYNOPSIS
    PRTG vCenter Advanced Sensor
  
  .DESCRIPTION
    Advanced Sensor will Report vCenter Statistics about Resource usage.

        
  .EXAMPLE
    PRTG-vCenter.ps1 -VIServer vCenter.lan.local -Check DS
	
  .PARAMETER -VIServer vCenter.lan.local
    Specify the vCenter Host FQDN
	(vCenter.lan.local).	

  .PARAMETER -Check DS
    Specify the vCenter Check
	(DS, Cluster).
	
  .Notes
    NAME:  PRTG-vCenter.ps1
    LASTEDIT: 04/04/2016
    VERSION: 1.0
    KEYWORDS: PRTG-vCenter
   
  .Link
     https://mycloudrevolution.wordpress.com/
 
 #Requires PS -Version 2.0
 
 #>
[cmdletbinding()]
param(
    [Parameter(Position=0, Mandatory=$true)]
    [string] $VIServer,

    [Parameter(Position=1, Mandatory=$false)]
    [string] $Check

)

# Start Load VMware  Snapin (if not already loaded)
if (!(Get-PSSnapin -Name VMware.VimAutomation.Core -ErrorAction SilentlyContinue)) {
	if (!(Add-PSSnapin -PassThru VMware.VimAutomation.Core)) {
		# Error out if loading fails
		Write-Error "ERROR: Cannot load the VMware Snapin. Is the PowerCLI installed?"
		Exit
	}
}
# End Load VMware  Snapin (if not already loaded)

# Start Global Definitions
#Datastore to Ignore in DS Check
$DatastoreIgnore = "esx"
#Datastore to Ignore in Cluster Check
$ClusterIgnore = "STANDBY"
#Max CPU usage for non HA cluster
$limitResourceCPUClusNonHA = 0.6
#Max MEM usage for non HA cluster
$limitResourceMEMClusNonHA = 0.6
# End Global Definitions

# Start vCenter Connection
Write-Host "Starting to Process vCenter Connection to " $VIServer " ..."-ForegroundColor Magenta
$OpenConnection = $global:DefaultVIServers | where { $_.Name -eq $VIServer }
if($OpenConnection.IsConnected) {
	Write-Host "vCenter is Already Connected..." -ForegroundColor Yellow
	$VIConnection = $OpenConnection
} else {
	Write-Host "Connecting vCenter..."
	$VIConnection = Connect-VIServer -Server $VIServer
}

if (-not $VIConnection.IsConnected) {
	Write-Error "Error: vCenter Connection Failed"
    Exit
}
# End vCenter Connection


If ($Check -eq "DS") {
    New-VIProperty -Name PercentFree -ObjectType Datastore -Value {
	param($ds)
	[math]::Round(((100 * ($ds.FreeSpaceMB)) / ($ds.CapacityMB)),0)
    } -Force | Out-Null

    $Datastores = Get-Datastore  | where {$_.State -eq "Available" -and $_.Accessible -eq "True"}
    $OutputDatastores = @($Datastores | Where-Object {$_.Name -notmatch $DatastoreIgnore} | Select-Object Name, PercentFree| Sort-Object Name)
    
    Write-Host "<prtg>" 
    foreach ($OutputDatastore in $OutputDatastores){
        $Name = "DS - " + $OutputDatastore.Name
        $Free = $OutputDatastore.PercentFree
        Write-Host "<result>"
               "<channel>$Name</channel>"
               "<value>$Free</value>"
               "<unit>Percent</unit>"
               "<showChart>1</showChart>"
               "<showTable>1</showTable>"
               "<LimitMinWarning>20</LimitMinWarning>"
               "<LimitMinError>10</LimitMinError>"
               "<LimitMode>1</LimitMode>"
               "</result>" 
	    }
    Write-Host "</prtg>" 

    # $OutputDatastores | ft -AutoSize

    }

If ($Check -eq "Cluster") {
	$VM = Get-VM
	$clusviews = Get-View -ViewType ClusterComputeResource | Where-Object {$_.Name -notmatch $ClusterIgnore}
	$capacityinfo = @()
	foreach ($cluv in ($clusviews | Where {$_.Summary.NumHosts -gt 0 } | Sort Name)) {
	
	if ( $cluv.Configuration.DasConfig.Enabled -eq $true ) {
		$DasRealCpuCapacity = $cluv.Summary.EffectiveCpu - (($cluv.Summary.EffectiveCpu * $cluv.Configuration.DasConfig.FailoverLevel)/$cluv.Summary.NumHosts)
		$DasRealMemCapacity = $cluv.Summary.EffectiveMemory - (($cluv.Summary.EffectiveMemory * $cluv.Configuration.DasConfig.FailoverLevel)/$cluv.Summary.NumHosts)
	} else {
		$DasRealCpuCapacity = $cluv.Summary.EffectiveCpu * $limitResourceCPUClusNonHA
		$DasRealMemCapacity = $cluv.Summary.EffectiveMemory * $limitResourceMEMClusNonHA
	}
	
	$cluvmlist = $VM | where { $cluv.Host -contains $_.VMHost.Id  }
	
	#CPU
	$CluCpuUsage = (get-view $cluv.ResourcePool).Summary.runtime.cpu.OverallUsage
	$CluCpuUsageAvg = $CluCpuUsage
	if ($cluvmlist -and $cluv.host -and $CluCpuUsageAvg -gt 0){
		$VmCpuAverage = $CluCpuUsageAvg/($cluvmlist.count)
		$CpuVmLeft = [math]::round(($DasRealCpuCapacity-$CluCpuUsageAvg)/$VmCpuAverage,0)
	}
	elseif ($CluCpuUsageAvg -eq 0) {$CpuVmLeft = "N/A"}
	else {$CpuVmLeft = 0}
	
	#MEM
	$CluMemUsage = (get-view $cluv.ResourcePool).Summary.runtime.memory.OverallUsage
	$CluMemUsageAvg = $CluMemUsage/1MB
	if ($cluvmlist -and $cluv.host -and $CluMemUsageAvg -gt 100){
		$VmMemAverage = $CluMemUsageAvg/(Get-Cluster $cluv.name|Get-VM).count
		$MemVmLeft = [math]::round(($DasRealMemCapacity-$CluMemUsageAvg)/$VmMemAverage,0)
	}
	elseif ($CluMemUsageAvg -lt 100) {$CluMemUsageAvg = "N/A"}
	else{$MemVmLeft = 0}
	
	# vCPU to pCPU ratio
	if ($cluvmlist){
		$vCPUpCPUratio = [math]::round(($cluvmlist|Measure-Object -Sum -Property NumCpu).sum / $cluv.summary.NumCpuThreads,0)
	}
	else { $vCPUpCPUratio = "0 (vCPU < pCPU)"}
	
	
	$clucapacity = [PSCustomObject] @{
		ClusterName = $cluv.name
		"Estimated Num VM Left (CPU)" = $CpuVmLeft
		"Estimated Num VM Left (MEM)" = $MemVmLeft
		"vCPU/pCPU ratio" =  $vCPUpCPUratio
	}
	
	$capacityinfo += $clucapacity
	}
	

    Write-Host "<prtg>" 
    foreach ($capacity in $capacityinfo){
        $Name = $capacity.ClusterName + " - VM Left (CPU)"
        $Value = $capacity."Estimated Num VM Left (CPU)"
        Write-Host "<result>"
               "<channel>$Name</channel>"
               "<value>$Value</value>"
               "<showChart>1</showChart>"
               "<showTable>1</showTable>"
               "<LimitMinWarning>10</LimitMinWarning>"
               "<LimitMinError>5</LimitMinError>"
               "<LimitMode>1</LimitMode>"
               "</result>" 

        $Name = $capacity.ClusterName + " - VM Left (MEM)"
        $Value = $capacity."Estimated Num VM Left (MEM)"
        Write-Host "<result>"
               "<channel>$Name</channel>"
               "<value>$Value</value>"
               "<showChart>1</showChart>"
               "<showTable>1</showTable>"
               "<LimitMinWarning>10</LimitMinWarning>"
               "<LimitMinError>5</LimitMinError>"
               "<LimitMode>1</LimitMode>"
               "</result>" 

        $Name = $capacity.ClusterName + " - vCPU/pCPU"
        $Value = $capacity."vCPU/pCPU ratio"
        Write-Host "<result>"
               "<channel>$Name</channel>"
               "<value>$Value</value>"
               "<showChart>1</showChart>"
               "<showTable>1</showTable>"
               "<LimitMaxWarning>3</LimitMaxWarning>"
               "<LimitMaxError>4</LimitMaxError>"
               "<LimitMode>1</LimitMode>"
               "</result>" 
	    }
    Write-Host "</prtg>" 

	# $capacityinfo | Sort ClusterName | ft -AutoSize
}