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Introduction to Big Data and Hadoop

HDFS in Practice II

Explore how to use HDFS admin and daemon commands to manage and monitor Hadoop clusters. Understand topology inspection, retrieve reports, manage Datanode processes, and interact with HDFS uploads in a practical environment.

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HDFS in Practice II

In the previous lesson, we looked at some client commands. Now we’ll briefly explore admin and daemon commands offered by the hdfs command line utility.

Shell
# Startup Hadoop deamons
./DataJek/startHadoop.sh
# Retrieve the topology of the cluster
hdfs dfsadmin -printTopology
# Get an admin report
hdfs dfsadmin -report
# Get the status of a Datanode
hdfs dfsadmin -getDatanodeInfo localhost:9867
# Retrieve the FS image
hdfs dfsadmin -fetchImage /Downloads
# Attempt to start the Datanode
hdfs datanode
Terminal 1
Terminal
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  • Serious production deployments of Hadoop are deployed on a cluster of machines with a planned topology. HDFS looks at the topology of the Datanodes when placing the data block’s replicas. We can examine the topology with this following command:

    hdfs dfsadmin
...