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
    
        
            fs.defaultFS
            hdfs://192.168.137.130:9000    # 配置自己机器的IP
        
    
    
    [hadoop@hadoop-01 hadoop]# vi etc/hadoop/hdfs-site.xml
    
        
            dfs.replication
            1
        
    
  

• 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
    
        dfs.namenode.secondary.http-address
        hadoop-01:50090
    
    
        dfs.namenode.secondary.https-address
        hadoop-01:50091
    
    
    # 重启
    [hadoop@hadoop-01 hadoop]# sbin/stop-dfs.sh
    [hadoop@hadoop-01 hadoop]# sbin/start-dfs.sh