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

You need to check :

/app/hadoop/tmp/dfs/data/current/VERSION and /app/hadoop/tmp/dfs/name/current/VERSION ---

in those two files and that to Namespace ID of name node and datanode.

If and only if data node's NamespaceID is same as name node's NamespaceID then your datanode will run.

If those are different copy the namenode NamespaceID to your Datanode's NamespaceID using vi editor or gedit and save and re run the deamons it will work perfectly.