title: quartz jobDetail requestRecovery
body: <p>The documentation for <code>JobDetail.requestsRecovery</code> property states the following </p>
  
  <blockquote>
    <p>Instructs the Scheduler whether or not the Job  should be re-executed
    if a 'recovery' or 'fail-over' situation is encountered.</p>
  </blockquote>
  
  <p>Now, what is a 'recovery' situation or a 'fail-over' situation?</p>
  
  <p>How are they different? </p>
  
  <p>Does the recovery happen only if the JVM crashes during job execution or does it happen if the job execution fails because of an exception also? </p>