Unlike the local mode of Hadoop, where all the components run only for the lifetime of the submitted job, with the pseudo-distributed or fully distributed mode of Hadoop, the cluster components exist as long-running processes. Before we use HDFS or MapReduce, we need to start up the needed components. Type the following commands; the output should look as shown next, where the commands are included on the lines prefixed by $:
Type in the first command:
$ start-dfs.sh starting namenode, logging to /home/hadoop/hadoop/bin/../logs/hadoop-hadoop-namenode-vm193.out localhost: starting datanode, logging to /home/hadoop/hadoop/bin/../logs/hadoop-hadoop-datanode-vm193.out localhost: starting secondarynamenode, logging to /home/hadoop/hadoop/bin/../logs/hadoop-hadoop-secondarynamenode-vm193.out
Type in the second command:
$ jps 9550 DataNode 9687 Jps 9638 SecondaryNameNode 9471 NameNode
Type in the third command:
$ hadoop dfs -ls / Found 2 items drwxr-xr-x - hadoop...