HOWTO: Test HDFS Setup

ISSUE

How do I run simple Hadoop Distributed File System tasks? Or

How do I test that HDFS services are working?

SOLUTION

Make sure the name node and the data nodes are started.

To start the name node:

su hdfs - -c "hadoop-daemon.sh --config /etc/hadoop/ start namenode"

To start a data node:

su hdfs - -c "hadoop-daemon.sh --config /etc/hadoop start datanode"

Put data files into HDFS. This command will take a file from disk and put into HDFS:

su hdfs
hadoop fs -put trial_file.csv /user/hdfs/trial_file.csv

Read data from HDFS. This command will read the contents of a file from HDFS and display on the console:

su hdfs
hadoop fs -cat /user/hdfs/trial_file.csv

References:

http://hadoop.apache.org/common/docs/current/file_system_shell.html

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