title: Calculating percentage with Grafana/Graphite
body: <p>I'm struggling with calculating the percentage of a list of servers.</p>
  
  <p>What I have is:</p>
  
  <pre><code>icinga2.$server.services.Memory_Load.memory-windows.perfdata.memory.value
  </code></pre>
  
  <p>and</p>
  
  <pre><code>icinga2.$server.services.Memory_Load.memory-windows.perfdata.memory.max
  </code></pre>
  
  <p>I can't figure out how to calculate a percentage from those values.</p>
  
  <p>Anyone can help me out?</p>
  
  <p>I tried to fool around with <code>reduceSeries</code>, <code>mapSeries</code> and <code>asPercent</code> but always get a query error out of it.</p>
  
  <p>Example I tried:</p>
  
  <pre><code>reduceSeries(mapSeries(icinga2.$server.services.Memory_Load.memory-windows.perfdata.memory.*,1),"asPercent",3,"value","max")
  </code></pre>
  
  <p>Thanks in advance</p>