HADOOP – HOT INTERVIEW QUESTIONS - What is the responsibility of name node in HDFS?

1. Name node is the master daemon for creating metadata for blocks stored on data nodes.
2. Every data node sends heartbeat and block report to Name node.
3. If Name node does not receive any heartbeat then it simply identifies that the data node is dead. The Name node is the single point of failure. Without Name node there is no metadata and the Job Tracker can’t assign tasks to the Task Trackers.
4. If Name node goes down HDFS cluster in inaccessible. There is no way for the client to identify which data node has free space as there is no metadata available in the data node.