Peter, > I'm getting the following errors: > > WARN org.apache.hadoop.mapred.JobTracker: Serious problem, cannot find record > of 'previous' heartbeat for > 'tracker_m351.ra.wink.com:localhost/127.0.0.1:41885'; > reinitializing the tasktracker > > INFO org.apache.hadoop.mapred.JobTracker: Adding task > 'attempt_201005271529_0004_r_000042_1' to tip > task_201005271529_0004_r_000042, for tracker > 'tracker_m351.ra.wink.com:localhost/127.0.0.1:41885' > > INFO org.apache.hadoop.mapred.JobTracker: Removed completed task > 'attempt_201005271529_0004_m_000112_0' from > 'tracker_m351.ra.wink.com:localhost/127.0.0.1:41885' > > > despite not having m351 in any of the config files except racks.txt. > If I take it out of there I can't start any jobs at all. > > Question is - what would make a machine be contacted as a tasktracker when it > is not in the slave or *.xml files? >
If m351 has Hadoop and a mapred-site.xml or hadoop-site.xml pointing to the right JobTracker, it would register itself as a TaskTracker when Hadoop starts on it. The slave file is used primarily to start the daemons from a central place and is not a way to specify which nodes must join the Hadoop cluster. Thanks hemanth
