Hadoop：2、Hadoop伪分布式部署(HDFS)

Hadoop部署的三种模式：

单机模式（standalone）

一般不建议安装，网络上很少这方面资料

单机模式是Hadoop的默认模式。当首次解压Hadoop的源码包时，Hadoop无法了解硬件安装环境，便保守地选择了最小配置。
在这种默认模式下所有3个XML文件均为空。当配置文件为空时，Hadoop会完全运行在本地。
因为不需要与其他节点交互，单机模式就不使用HDFS，也不加载任何Hadoop的守护进程。
该模式主要用于开发调试MapReduce程序的应用逻辑。

伪分布模式（Pseudo-Distributed Mode）

  伪分布模式在“单节点集群”上运行Hadoop，其中所有的守护进程都运行在同一台机器上。
  该模式在单机模式之上增加了代码调试功能，允许你检查内存使用情况，HDFS输入输出，以及其他的守护进程交互。
  比如namenode，datanode，secondarynamenode，jobtracer，tasktracer这5个进程，都能在集群上看到。

全分布模式（Fully Distributed Mode）

  Hadoop守护进程运行在一个集群上。
  意思是说master上看到namenode,jobtracer，secondarynamenode可以安装在master节点，也可以单独安装。slave节点能看到datanode和tasktracer

Hadoop伪分布模式部署

环境要求java、ssh

添加hadoop用户

  [root@hadoop-01 ~]# useradd hadoop
  [root@hadoop-01 ~]# vi /etc/sudoers
  # 找到root    ALL=(ALL)   ALL，添加
  hadoop  ALL=(ALL)       NOPASSWD:ALL

上传并解压

  [root@hadoop-01 software]# rz #上传hadoop-2.8.1.tar.gz
  [root@hadoop-01 software]# tar -xzvf hadoop-2.8.1.tar.gz

软连接

  [root@hadoop-01 software]# ln -s /opt/software/hadoop-2.8.1 /opt/software/hadoop

设置环境变量

  [root@hadoop-01 software]# vi /etc/profile
  export HADOOP_HOME=/opt/software/hadoop
  export PATH=$HADOOP_HOME/bin:$HADOOP_HOME/sbin:$PROTOC_HOME/bin:$FINDBUGS_HOME/bin:$MAVEN_HOME/bin:$JAVA_HOME/bin:$PATH
  [root@hadoop-01 software]# source /etc/profile

设置用户用户组

  [root@hadoop-01 software]# chown -R hadoop:hadoop hadoop
  [root@hadoop-01 software]# chown -R hadoop:hadoop hadoop/*
  [root@hadoop-01 software]# chown -R hadoop:hadoop hadoop-2.8.1
          
  [root@hadoop-01 software]# cd hadoop
  [root@hadoop-01 hadoop]# rm -f *.txt

切换用户hadoop

  [root@hadoop-01 software]# su - hadoop
  [root@hadoop-01 hadoop]# ll
  total 32
  drwxrwxr-x. 2 hadoop hadoop 4096 Jun  2 14:24 bin
  drwxrwxr-x. 3 hadoop hadoop 4096 Jun  2 14:24 etc
  drwxrwxr-x. 2 hadoop hadoop 4096 Jun  2 14:24 include
  drwxrwxr-x. 3 hadoop hadoop 4096 Jun  2 14:24 lib
  drwxrwxr-x. 2 hadoop hadoop 4096 Aug 20 13:59 libexec
  drwxr-xr-x. 2 hadoop hadoop 4096 Aug 20 13:59 logs
  drwxrwxr-x. 2 hadoop hadoop 4096 Jun  2 14:24 sbin
  drwxrwxr-x. 4 hadoop hadoop 4096 Jun  2 14:24 share 
  
  # bin:      可执行文件
  # etc:      配置文件
  # sbin:     shell脚本，启动关闭hdfs,yarn等

配置文件

  [hadoop@hadoop-01 ~]# cd /opt/software/hadoop
  [hadoop@hadoop-01 hadoop]# vi etc/hadoop/core-site.xml
  <configuration>
      <property>
          <name>fs.defaultFS</name>
          <value>hdfs://192.168.137.130:9000</value>    # 配置自己机器的IP
      </property>
  </configuration>
  
  [hadoop@hadoop-01 hadoop]# vi etc/hadoop/hdfs-site.xml
  <configuration>
      <property>
          <name>dfs.replication</name>
          <value>1</value>
      </property>
  </configuration>

配置hadoop用户的ssh信任关系

  # 公钥/密钥   配置无密码登录
  [hadoop@hadoop-01 ~]# ssh-keygen -t rsa -P '' -f ~/.ssh/id_rsa
  [hadoop@hadoop-01 ~]# cat ~/.ssh/id_rsa.pub >> ~/.ssh/authorized_keys
  [hadoop@hadoop-01 ~]# chmod 0600 ~/.ssh/authorized_keys
  
  # 查看日期，看是否配置成功
  [hadoop@hadoop-01 ~]# ssh hadoop-01 date
  The authenticity of host 'hadoop-01 (192.168.137.130)' can't be established.
  RSA key fingerprint is 09:f6:4a:f1:a0:bd:79:fd:34:e7:75:94:0b:3c:83:5a.
  Are you sure you want to continue connecting (yes/no)? yes   # 第一次回车输入yes
  Warning: Permanently added 'hadoop-01,192.168.137.130' (RSA) to the list of known hosts.
  Sun Aug 20 14:22:28 CST 2017
  
  [hadoop@hadoop-01 ~]# ssh hadoop-01 date   #不需要回车输入yes,即OK
  Sun Aug 20 14:22:29 CST 2017
  
  [hadoop@hadoop-01 ~]# ssh localhost date
  The authenticity of host 'hadoop-01 (192.168.137.130)' can't be established.
  RSA key fingerprint is 09:f6:4a:f1:a0:bd:79:fd:34:e7:75:94:0b:3c:83:5a.
  Are you sure you want to continue connecting (yes/no)? yes   # 第一次回车输入yes
  Warning: Permanently added 'hadoop-01,192.168.137.130' (RSA) to the list of known hosts.
  Sun Aug 20 14:22:28 CST 2017
  [hadoop@hadoop-01 ~]# ssh localhost date   #不需要回车输入yes,即OK
  Sun Aug 20 14:22:29 CST 2017

格式化和启动

  [hadoop@hadoop-01 hadoop]# bin/hdfs namenode -format
  [hadoop@hadoop-01 hadoop]# sbin/start-dfs.sh
  ERROR:
      hadoop-01: Error: JAVA_HOME is not set and could not be found.
      localhost: Error: JAVA_HOME is not set and could not be found.
  解决方法:添加环境变量
  [hadoop@hadoop-01 hadoop]#  vi etc/hadoop/hadoop-env.sh
  # 将export JAVA_HOME=${JAVA_HOME}改为
  export JAVA_HOME=/usr/java/jdk1.8.0_45
  
  [hadoop@hadoop-01 hadoop]# sbin/start-dfs.sh
  ERROR:
      mkdir: cannot create directory `/opt/software/hadoop-2.8.1/logs': Permission denied
  解决方法:
  [hadoop@hadoop-01 hadoop]# exit
  [root@hadoop-01 hadoop]# cd ../
  [root@hadoop-01 software]# chown -R hadoop:hadoop hadoop-2.8.1
  [root@hadoop-01 software]# su - hadoop
  [root@hadoop-01 ~]# cd /opt/software/hadoop
  
  # 继续启动
  [hadoop@hadoop-01 hadoop]# sbin/start-dfs.sh

检查是否成功

  [hadoop@hadoop-01 hadoop]# jps
  19536 DataNode
  19440 NameNode
  19876 Jps
  19740 SecondaryNameNode

访问： http://192.168.137.130:50070

修改dfs启动的进程，以hadoop-01启动

  启动的三个进程：
  namenode: hadoop-01    bin/hdfs getconf -namenodes
  datanode: localhost    datanodes (using default slaves file)   etc/hadoop/slaves
  secondarynamenode: 0.0.0.0
  
  [hadoop@hadoop-01 ~]# cd /opt/software/hadoop
  [hadoop@hadoop-01 hadoop]# echo  "hadoop-01" > ./etc/hadoop/slaves 
  [hadoop@hadoop-01 hadoop]# cat ./etc/hadoop/slaves 
  hadoop-01
  
  [hadoop@hadoop-01 hadoop]# vi ./etc/hadoop/hdfs-site.xml
  <property>
      <name>dfs.namenode.secondary.http-address</name>
      <value>hadoop-01:50090</value>
  </property>
  <property>
      <name>dfs.namenode.secondary.https-address</name>
      <value>hadoop-01:50091</value>
  </property>
  
  # 重启
  [hadoop@hadoop-01 hadoop]# sbin/stop-dfs.sh
  [hadoop@hadoop-01 hadoop]# sbin/start-dfs.sh