*Hi, NameNode* serves as a directory namespace manager. It keeps the directory tree of all files in the file system, and tracks where across the cluster the file data is kept. It does not store the data of these files itself.
whereas a jobtracker manages job-related parameters. "The JobTracker is the service within Hadoop that farms out MapReduce<http://wiki.apache.org/hadoop/MapReduce>tasks to specific nodes in the cluster, ideally the nodes that have the data, or at least are in the same rack. 1. Client applications submit jobs to the Job tracker. 2. The JobTracker talks to the NameNode<http://wiki.apache.org/hadoop/NameNode>to determine the location of the data 3. The JobTracker locates TaskTracker<http://wiki.apache.org/hadoop/TaskTracker>nodes with available slots at or near the data 4. The JobTracker submits the work to the chosen TaskTracker<http://wiki.apache.org/hadoop/TaskTracker>nodes." [source: http://wiki.apache.org/hadoop/JobTracker] Best, Jonna
