Datanode process not running in Hadoop

Question

I set up and configured a multi-node Hadoop cluster using this tutorial.

When I type in the start-all.sh command, it shows all the processes initializing properly as

Answer 1

Once I was not able to find data node using jps in hadoop, then I deleted the current folder in the hadoop installed directory (/opt/hadoop-2.7.0/hadoop_data/dfs/data) and restarted hadoop using start-all.sh and jps.

This time I could find the data node and current folder was created again.