Environment construction of Hadoop3.2.1 version

Recently, someone asked if they could post some knowledge about big data. No problem! Today, start from the installation environment, build up their own learning environment.

Three ways to build And use Hadoop:

Stand-alone version suitable for development and debugging;
Pseudo-distributed is suitable for simulating cluster learning;
Fully distributed for production environments.

This document describes how to build a fully distributed Hadoop cluster with one master node and two data nodes.

A prerequisite for

Prepare three servers

Virtual machines, physical machines, and cloud instances can be used. Three instances in Openstack private cloud are used for installation and deployment.

Operating system and software version

The server	system	memory	IP	planning	JDK	HADOOP
node1	Ubuntu 18.04.2 LTS	8G	10.101.18.21	master	The JDK 1.8.0 comes with _222	Hadoop – 3.2.1
node2	Ubuntu 18.04.2 LTS	8G	10.101.18.8	slave1	The JDK 1.8.0 comes with _222	Hadoop – 3.2.1
node3	Ubuntu 18.04.2 LTS	8G	10.101.18.24	slave2	The JDK 1.8.0 comes with _222	Hadoop – 3.2.1

JDK installed on three machines

Since Hadoop is written in the Java language, a Java environment needs to be installed on your computer. I used JDK 1.8.0_222 here (Sun JDK is recommended)

Install command

sudo apt install openjdk-8-jdk-headless
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To configure the JAVA environment variable, add the following to the bottom of the.profile file in the current user root directory:

export JAVA_HOME=/usr/lib/jvm/java-8-openjdk-amd64
export PATH=$JAVA_HOME/bin:$PATH
export CLASSPATH=.:$JAVA_HOME/lib/dt.jar:$JAVA_HOME/lib/tools.jar
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Use the source command to make it effective immediately

source .profile
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The host configuration

Modify the hosts files of the three servers

vim /etc/hosts

Add the following, based on the individual server IP

10.101.18.21 master
10.101.18.8 slave1
10.101.18.24 slave2
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Secret free login configuration

Production of the secret key

ssh-keygen -t rsa
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Master logs in to slave in non-secret mode

ssh-copy-id -i ~/.ssh/id_rsa.pub master
ssh-copy-id -i ~/.ssh/id_rsa.pub slave1
ssh-copy-id -i ~/.ssh/id_rsa.pub slave2
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Test secret free login

ssh master 
ssh slave1
ssh slave2
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Hadoop structures,

We download the Hadoop package from the Master node, modify the configuration, and then copy it to other Slave nodes for minor modifications.

Download the installation package and create a Hadoop directory

# downloadWget HTTP: / / http://http://apache.claz.org/hadoop/common/hadoop-3.2.1//hadoop-3.2.1.tar.gzUnzip to /usr/localSudo tar -xzvf hadoop-3.2.1. Tar. gz -c /usr/local 
# Change hadoop file permissionsSudo chown -r Ubuntu: Ubuntu hadoop-3.2.1. Tar.gzRename the folderSudo mv hadoop - 3.2.1 hadoopCopy the code

Configure Hadoop environment variables for the Master node

As with JDK environment variables, edit the.profile file in the user directory to add Hadoop environment variables:

export HADOOP_HOME=/usr/local/hadoop
export PATH=$PATH:$HADOOP_HOME/bin 
export HADOOP_CONF_DIR=$HADOOP_HOME/etc/hadoop
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Execute source.profile for immediate effect

Configuring the Master Node

All components of Hadoop with the XML file configuration, configuration files in the/usr/local/Hadoop/etc/Hadoop directory:

Core-site. XML: configures common properties, such as I/O Settings used by HDFS and MapReduce
Hdfs-site. XML: Hadoop daemon configuration, including Namenode, auxiliary Namenode, and Datanode
Mapred-site. XML: MapReduce daemon configuration
Yarn-site. XML: configures resource scheduling

A. Modify the core-site. XML file as follows:

<configuration>
    <property>
        <name>hadoop.tmp.dir</name>
        <value>file:/usr/local/hadoop/tmp</value>
        <description>Abase for other temporary directories.</description>
    </property>
    <property>
        <name>fs.defaultFS</name>
        <value>hdfs://master:9000</value>
    </property>
</configuration>
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Parameter Description:

Fs. defaultFS: indicates the default file system. This parameter is required for HDFS clients to access HDFS
Hadoop.tmp. dir: specifies the temporary directory of the Hadoop data store. Other directories will be based on this directory

If hadoop.tmp.dir is not configured, the system uses the default temporary directory/TMP /hadoo-hadoop. This directory will be deleted after each restart. You must re-run format to avoid errors.

B. Edit hdfs-site. XML as follows:

<configuration>
    <property>
        <name>dfs.replication</name>
        <value>3</value>
    </property>
    <property>
        <name>dfs.name.dir</name>
        <value>/usr/local/hadoop/hdfs/name</value>
    </property>
    <property>
        <name>dfs.data.dir</name>
        <value>/usr/local/hadoop/hdfs/data</value>
    </property>
</configuration>
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Parameter Description:

Dfs. replication: number of copies of data blocks
Dfs.name. dir: specifies the file storage directory of the namenode node
Dfs.data. dir: specifies the file storage directory of datanode

C. Edit mapred-site. XML as follows:

<configuration>
  <property>
      <name>mapreduce.framework.name</name>
      <value>yarn</value>
  </property>
  <property>
    <name>mapreduce.application.classpath</name>
    <value>$HADOOP_HOME/share/hadoop/mapreduce/*:$HADOOP_HOME/share/hadoop/mapreduce/lib/*</value>
  </property>
</configuration>
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D. Edit yarn-site. XML and make the following changes:

<configuration>
<! -- Site specific YARN configuration properties -->
    <property>
        <name>yarn.nodemanager.aux-services</name>
        <value>mapreduce_shuffle</value>
    </property>
    <property>
            <name>yarn.resourcemanager.hostname</name>
            <value>master</value>
    </property>
    <property>
        <name>yarn.nodemanager.env-whitelist</name>
        <value>JAVA_HOME,HADOOP_COMMON_HOME,HADOOP_HDFS_HOME,HADOOP_CONF_DIR,CLASSPATH_PREPEND_DISTCACHE,HADOOP_YARN_HOME,HADOOP_HOME</value>
    </property>
</configuration>
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E. Edit workers and modify as follows:

slave1
slave2
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Configuring the Worker node

Configuring the Slave Node

Package the Hadoop configured on the Master node and send it to the other two nodes:

# Hadoop package
tar -cxf hadoop.tar.gz /usr/local/hadoop
Copy to the other two nodes
scp hadoop.tar.gz ubuntu@slave1:~
scp hadoop.tar.gz ubuntu@slave2:~
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Pressurize Hadoop packages on other nodes to /usr/local

sudo tar -xzvf hadoop.tar.gz -C /usr/local/
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Configure Hadoop environment variables for Slave1 and Slaver2:

export HADOOP_HOME=/usr/local/hadoop
export PATH=$PATH:$HADOOP_HOME/bin 
export HADOOP_CONF_DIR=$HADOOP_HOME/etc/hadoop
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Start the cluster

Format the HDFS file system

Go to the Hadoop directory on the Master node and perform the following operations:

bin/hadoop namenode -format
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Format the Namenode. The operations performed before starting the service for the first time do not need to be performed later.

Truncate part of the log (see line 5 log to indicate formatting success) :

2019-11-11 13:34:18.960 INFO util.GSet: VM type       = 64-bit
2019-11-11 13:34:18.960 INFO util.GSet: 0.029999999329447746% max memory 1.7 GB = 544.5 KB
2019-11-11 13:34:18.961 INFO util.GSet: capacity      = 2^16 = 65536 entries
2019-11-11 13:34:18.994 INFO namenode.FSImage: Allocated new BlockPoolId: BP-2017092058-10.10118.21 -1573450458983
2019-11-11 13:34:19.010 INFO common.Storage: Storage directory /usr/local/hadoop/hdfs/name has been successfully formatted.
2019-11-11 13:34:19.051 INFO namenode.FSImageFormatProtobuf: Saving image file /usr/local/hadoop/hdfs/name/current/fsimage.ckpt_0000000000000000000 using no compression
2019-11-11 13:34:19.186 INFO namenode.FSImageFormatProtobuf: Image file /usr/local/hadoop/hdfs/name/current/fsimage.ckpt_0000000000000000000 of size 401 bytes saved in 0 seconds .
2019-11-11 13:34:19.207 INFO namenode.NNStorageRetentionManager: Going to retain 1 images with txid >= 0
2019-11-11 13:34:19.214 INFO namenode.FSImage: FSImageSaver clean checkpoint: txid=0 when meet shutdown.
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Starting a Hadoop Cluster

sbin/start-all.sh
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Problems and solutions during startup:

Error: master: RCMD: socket: Permission denied

Solution:

Run echo “SSH” > /etc/pdsh/rcmd_default

B. error: JAVA_HOME is not set and could not be found.

Solution:

Modify hadoop-env.sh for the three nodes and add the following JAVA environment variables

export JAVA_HOME=/usr/lib/jvm/java-8-openjdk-amd64
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Run the JPS command to check the running status

The Master node executes output:

19557 ResourceManager
19914 Jps
19291 SecondaryNameNode
18959 NameNode
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Slave Node execution input:

18580 NodeManager
18366 DataNode
18703 Jps
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View the Hadoop cluster status

hadoop dfsadmin -report
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View the results:

Configured Capacity: 41258442752 (38.42 GB)
Present Capacity: 5170511872 (4.82 GB)
DFS Remaining: 5170454528 (4.82 GB)
DFS Used: 57344 (56 KB)
DFS Used%: 0.00%
Replicated Blocks:
	Under replicated blocks: 0
	Blocks with corrupt replicas: 0
	Missing blocks: 0
	Missing blocks (with replication factor 1): 0
	Low redundancy blocks with highest priority to recover: 0
	Pending deletion blocks: 0
Erasure Coded Block Groups: 
	Low redundancy block groups: 0
	Block groups with corrupt internal blocks: 0
	Missing block groups: 0
	Low redundancy blocks with highest priority to recover: 0
	Pending deletion blocks: 0

-------------------------------------------------
Live datanodes (2):

Name: 10.101.18.24:9866 (slave2)
Hostname: slave2
Decommission Status : Normal
Configured Capacity: 20629221376 (19.21 GB)
DFS Used: 28672 (28 KB)
Non DFS Used: 16919797760 (15.76 GB)
DFS Remaining: 3692617728 (3.44 GB)
DFS Used%: 0.00%
DFS Remaining%: 17.90%
Configured Cache Capacity: 0 (0 B)
Cache Used: 0 (0 B)
Cache Remaining: 0 (0 B)
Cache Used%: 100.00%
Cache Remaining%: 0.00%
Xceivers: 1
Last contact: Mon Nov 11 15:00:27 CST 2019
Last Block Report: Mon Nov 11 14:05:48 CST 2019
Num of Blocks: 0


Name: 10.101.18.8:9866 (slave1)
Hostname: slave1
Decommission Status : Normal
Configured Capacity: 20629221376 (19.21 GB)
DFS Used: 28672 (28 KB)
Non DFS Used: 19134578688 (17.82 GB)
DFS Remaining: 1477836800 (1.38 GB)
DFS Used%: 0.00%
DFS Remaining%: 7.16%
Configured Cache Capacity: 0 (0 B)
Cache Used: 0 (0 B)
Cache Remaining: 0 (0 B)
Cache Used%: 100.00%
Cache Remaining%: 0.00%
Xceivers: 1
Last contact: Mon Nov 11 15:00:24 CST 2019
Last Block Report: Mon Nov 11 13:53:57 CST 2019
Num of Blocks: 0
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Close the Hadoop

sbin/stop-all.sh
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Web View The Hadoop cluster status

Enter http://10.101.18.21:9870 in your browser. The result is as follows:

Enter http://10.101.18.21:8088 in your browser. The result is as follows:

JAVA class at 9:30
data

Environment construction of Hadoop3.2.1 version

A prerequisite for

Secret free login configuration

Hadoop structures,

Start the cluster

Web View The Hadoop cluster status

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