1. How Datanode sends heartbeat to Namenode? Wil datanode communicate directly to NN or DataNode will communicate to Tasktracker, from tasktracker moves to Job Tracker from Job tracker heartbeat will be communicated to Namenode?
2. How unstructed data processed in MapReduce?
3. If DataNode goes down with Namenode still alive, how the communication will happen to Namenode? (practically)