title: rsync --sparse does transfer whole data
body: <p>I have some VM Images that need to synced everyday. The VM files are sparse'd.</p>
  
  <p>To save network traffic i only want to transfer the real datas of the images. 
  I try it with --sparse option at rsync but on network traffic i see that the whole size get transfered over network and not only the real data usage.</p>
  
  <p>If i use rsync -zv --sparse then only the real size get transmitted over network and everything is ok. But i dont want to compression the file because of the cpu usage.</p>
  
  <p>Shouldnt the --sparse option transfer only real datas and the "null datas" get created locally to save network traffic?</p>
  
  <p>Is there a workaround without compression?</p>
  
  <p>Thanks!</p>