My first guess is that it cannot find a datanode. When you visit the HDFS service in Cloudera Manager, look at "instances". Do you see any Datanodes? If you do - ensure the roles are started - try a simple "hadoop fs -put" from one of the nodes and try to add a file to HDFS If you don't see any Datanodes, then add the roles to the slave nodes and restart the HDFS service. ... View more