Step-by-Step Hadoop Environment Setup and Configuration on Three Linux Servers

First, edit the /etc/hosts file on each server to map the IP addresses 192.168.21.234, 192.168.21.235, and 192.168.21.236 to hostnames hd01, hd02, and hd03 respectively, and configure password‑less SSH between the three machines.

Install JDK 1.8 on hd01, hd02 and hd03.

On each node, modify Hadoop directories and permissions:

[root@hd01 hadoop]# cd /usr/local/hadoop/

[root@hd01 hadoop]# mkdir tmp

[root@hd01 hadoop]# chown -R 1000:1000 tmp/

[root@hd01 hadoop]# cd /usr/local/hadoop/etc/hadoop

Configure core-site.xml (replace the placeholder with your namenode address):

<configuration>
  <property>
    <name>fs.defaultFS</name>
    <value>hdfs://192.168.21.234:9000</value>
  </property>
  <property>
    <name>hadoop.tmp.dir</name>
    <value>/usr/local/hadoop/tmp</value>
  </property>
</configuration>

Configure hdfs-site.xml to set replication factor and disable permission checks:

<configuration>
  <property>
    <name>dfs.replication</name>
    <value>1</value>
  </property>
  <property>
    <name>dfs.permissions</name>
    <value>false</value>
  </property>
</configuration>

Configure mapred-site.xml to use YARN as the MapReduce framework:

<configuration>
  <property>
    <name>mapreduce.framework.name</name>
    <value>yarn</value>
  </property>
</configuration>

Configure yarn-site.xml with the resource manager hostname and auxiliary services:

<configuration>
  <property>
    <name>yarn.resourcemanager.hostname</name>
    <value>hd01</value>
  </property>
  <property>
    <name>yarn.nodemanager.aux-services</name>
    <value>mapreduce_shuffle</value>
  </property>
</configuration>

Set the Java home in hadoop-env.sh: export JAVA_HOME=/usr/Java Format the HDFS namenode and start all Hadoop daemons:

[root@hd01 hadoop]# hdfs namenode -format

[root@hd01 hadoop]# start-all.sh

After the services start, open the Hadoop NameNode web UI at http://192.168.21.234:50070/dfshealth.html#tab-overview to verify the cluster status.