By default, Hadoop’s log level is set to INFO. This can be too much for most instances, as it will generate huge log files, even in an environment with low to moderate traffic. Changing the root logger in log4j.properties file in Hadoop will not change the log level.
Follow the steps below for changing the log level of Hadoop.
1. Shut down Hadoop if it is still running.
2. Open the [hadoop_home]/bin/hadoop-daemon.sh file. Look for the following line:
3. Modify that line to a lower or higher log level (WARN should be sufficient if the goal is to limit the size of the log file rather than debugging an issue).
4. Save the file and start Hadoop.