hadoop/hdfs/conf/hadoop-metrics2.properties

# syntax: [prefix].[source|sink].[instance].[options]
# See javadoc of package-info.java for org.apache.hadoop.metrics2 for details

*.sink.file.class=org.apache.hadoop.metrics2.sink.FileSink

#namenode.sink.file.filename=namenode-metrics.out

#datanode.sink.file.filename=datanode-metrics.out