title: Rrd4j persistence
body: <p>I am using rrd4j to do what rrd4j does, and it works great. However, if I shut down my app and start it back up again, the data from the previous session will be gone. </p>
  
  <p>I am using a normal file backend, like so:</p>
  
  <pre><code>RrdDef rrdDef = new RrdDef( "/path/to/my/file", 3000 );
  </code></pre>
  
  <p>Is there a setting or something I need to trigger to make rrd4j load the data from the previous session?</p>