Un-blacklisting a TaskTracker Manually

  1. If a TaskTracker is blacklisted per job, you can un-blacklist it by running the following command as the administrative user:
    hadoop job -unblacklist <jobid> <hostname> 
  2. If a TaskTracker has been blacklisted cluster-wide due to mapred.max.tracker.blacklists or using the hadoop job -blacklist-tracker <host> command, use the following command as the administrative user to remove that node from the blacklist:
    hadoop job -unblacklist-tracker <hostname>
    If a TaskTracker has been blacklisted cluster-wide due to a non-healthy status, correct the indicated problem and run the health check script again. When the script picks up the healthy status, the TaskTracker is un-blacklisted.