What if you do not set the property 'hadoop.tmp.dir'?
In Hadoop installation directory under the core-site.xml file in the conf directory there used to be a property 'hadoop.tmp.dir'. This property is used to define the directory at the local filesystem which will store the data for the namenode and the data node. There're three HDFS properties which contain hadoop.tmp.dir in their values- dfs.name.dir : directory where namenode stores its metadata, with default value ${hadoop.tmp.dir}/dfs/name . dfs.data.dir : directory where HDFS data blocks are stored, with default value ${hadoop.tmp.dir}/dfs/data . fs.checkpoint.dir : directory where secondary namenode store its checkpoints, default value is ${hadoop.tmp.dir}/dfs/namesecondary . Usually the default value for "hadoop.tmp.dir" is '/tmp/hadoop-{username}'. With many of the OS restarts, the 'tmp' directory contents are deleted and hence you may loose the data directory for the namenode as well as th datanode content. And then if you...