Is there a way to debug namenode or datanode of hadoop using eclipse?
You can find detailed information on this on the Developing Hadoop Wiki. It has detailed info on stuff like How To Setup Your Development Environment, How To Develop Unit Tests etc.
HTH
To debug hadoop daemons as opposed to How to debug hadoop mapreduce jobs from eclipse? then you can add Java debug options to the /etc/default/hadoop-daemon-name
E.g. to debug the name node add the following to /etc/default/hadoop-hdfs-namenode
export HADOOP_OPTS="$HADOOP_OPTS -agentlib:jdwp=transport=dt_socket,server=y,suspend=n,address=8000"Then you can remote connect to your namenode on port 8000 from eclipse.Obviously remove this after as it opens your name node to potential abuse from anywhere in the world!