Hortonworks and Hadoop Client Installation
If using Hortonworks, some versions of Ambari do not install some of the required JAR files on all DataNodes. Correct operation requires the Hadoop Client and Hadoop DataNode JARs to be installed.
The following command should return details similar to the following:
rpm -aq | grep hadoop | grep "client\|datanode"
hadoop_2_2_6_0_2800-client-2.6.0.2.2.6.0-2800.el6.x86_64
hadoop_2_2_6_0_2800-hdfs-datanode-2.6.0.2.2.6.0-2800.el6.x86_64
If these JARs are not installed on your installation by default, install them manually.