title: What does lineage warn mean?
body: <p>I have this warn on my spark-shell : </p>
  
  <p>"WARN lineage.LineageWriter: Lineage directory /var/log/spark2/lineage doesn't exist or is not writable. Lineage for this application will be disabled."</p>
  
  <p>I don't understand what it means.</p>
  
  <p>What are the consequences?
  Is it important?
  Do I have to do something to deal with that?</p>
  
  <p>Thank you</p>