title: RRD tool retrieve maximum value
body: <p>am trying to get the speed and maximum values for all of my interface using rrdtool using rrdtool fetch ... etc but the max value is for the standard time</p>
  
  <p>ex :</p>
  
  <p>rrdtool fetch xxx.rrd MAX -r 7200 -s 1357041600 -e now </p>
  
  <p>i just need to get the highest maximum value for 1 year</p>