I have installed and uninstalled ambari so many times coz of that UUID and clusterd id is different from namenode and datanodes. thats why namenode is not started and datanodes too. So I did rm -rf /opt/hadoop/hdfs/data/* /tmp/hadoop/hdfs/data/*, /var/hadoop/hdfs/data, /var/log/hadoop/hdfs/data, /var/log/audit/hadoop/hdfs/data/* sudo -u hdfs /usr/hdp/2.3.6.0-3796/hadoop/sbin/hadoop-daemon.sh --config /etc/hadoop/conf start namenode su root /usr/lib/hadoop/bin/hadoop-daemon.sh --config /etc/hadoop/conf start datanode By doing this I fixed my issue. Hopefull it will help someone. Thanks ... View more