hadoop的单机版测试和集群节点的搭建

Hadoop

• Hadoop实现了一个分布式文件系统（Hadoop Distributed FileSystem），简称HDFS。HDFS有高容错性的特点，并且设计用来部署在低廉的（low-cost）硬件上；而且它提供高吞吐量（highthroughput）来访问应用程序的数据，适合那些有着超大数据集（large dataset）的应用程序。HDFS放宽了（relax）POSIX的要求，可以以流的形式访问（streaming access）文件系统中的数据。

Hadoop技术原理

• Hdfs主要模块：NameNode、DataNode
• Yarn主要模块：ResourceManager、NodeManager

HDFS主要模块及运行原理：
1）NameNode：

• 功能：是整个文件系统的管理节点。维护整个文件系统的文件目录树，文件/目录的元数据和每个文件对应的数据块列表。接收用户的请求。

2）DataNode：

• 功能：是HA（高可用性）的一个解决方案，是备用镜像，但不支持热备

一、hadoop单机版测试

1.建立用户，设置密码

[root@server1 ~]# useradd -u 1000 hadoop
[root@server1 ~]# passwd hadoop

2.hadoop的安装配置

切换到hadoop用户解压安装包,我们需要将hadoop安装在hadoop用户中
[root@server1 ~]# mv hadoop-3.0.3.tar.gz jdk-8u181-linux-x64.tar.gz /home/hadoop
[root@server1 ~]# su - hadoop
[hadoop@server1 ~]$ ls
hadoop-3.0.3.tar.gz  jdk-8u181-linux-x64.tar.gz
[hadoop@server1 ~]$ tar zxf jdk-8u181-linux-x64.tar.gz 
[hadoop@server1 ~]$ ln -s jdk1.8.0_181/ java
[hadoop@server1 ~]$ tar zxf hadoop-3.0.3.tar.gz 
[hadoop@server1 ~]$ ln -s hadoop-3.0.3 hadoop
[hadoop@server1 ~]$ ls
hadoop        hadoop-3.0.3.tar.gz  jdk1.8.0_181
hadoop-3.0.3  java                 jdk-8u181-linux-x64.tar.gz

3.配置环境变量

[hadoop@server1 hadoop]$ pwd
/home/hadoop/hadoop/etc/hadoop
[hadoop@server1 hadoop]$ vim hadoop-env.sh 
 54 export JAVA_HOME=/home/hadoop/java

[hadoop@server1 ~]$ vim .bash_profile 
PATH=$PATH:$HOME/.local/bin:$HOME/bin:$HOME/java/bin
[hadoop@server1 ~]$ source .bash_profile 
[hadoop@server1 ~]$ jps    ##配置成功可以调用
2518 Jps

4.测试

[hadoop@server1 hadoop]$ pwd
/home/hadoop/hadoop
[hadoop@server1 hadoop]$ mkdir input
[hadoop@server1 hadoop]$ cp etc/hadoop/*.xml input/
[hadoop@server1 hadoop]$ bin/hadoop jar share/hadoop/mapreduce/hadoop-mapreduce-examples-3.0.3.jar grep input output 'dfs[a-z.]+'
[hadoop@server1 hadoop]$ cd output/
[hadoop@server1 output]$ ls
part-r-00000  _SUCCESS
[hadoop@server1 output]$ cat *
1	dfsadmin

二、伪分布式

1.编辑文件

[hadoop@server1 hadoop]$ pwd
/home/hadoop/hadoop/etc/hadoop
[hadoop@server1 hadoop]$ vim core-site.xml
<configuration>
    <property>
        <name>fs.defaultFS</name>
        <value>hdfs://localhost:9000</value>
    </property>
</configuration>

[hadoop@server1 hadoop]$ vim hdfs-site.xml
<configuration>
    <property>
        <name>dfs.replication</name>
        <value>1</value>     ##自己充当节点
    </property>
</configuration>

2.生成密钥做免密连接

[hadoop@server1 hadoop]$ ssh-keygen 
[hadoop@server1 hadoop]$ ssh-copy-id localhost
[hadoop@server1 ~]$ exit
logout
Connection to localhost closed.

3.格式化，并开启服务

[hadoop@server1 hadoop]$ bin/hdfs namenode -format
[hadoop@server1 hadoop]$ pwd
/home/hadoop/hadoop
[hadoop@server1 hadoop]$ cd sbin/
[hadoop@server1 sbin]$ ./start-dfs.sh 
[hadoop@server1 sbin]$ jps
3889 Jps
3766 SecondaryNameNode
3451 NameNode
3563 DataNode

4.浏览器查看http://172.25.26.1:9870

5.测试，创建目录，并上传

[hadoop@server1 hadoop]$ pwd
/home/hadoop/hadoop
[hadoop@server1 hadoop]$ bin/hdfs dfs -mkdir -p /user/hadoop
[hadoop@server1 hadoop]$ bin/hdfs dfs -ls
[hadoop@server1 hadoop]$ 

[hadoop@server1 hadoop]$ bin/hdfs dfs -put input
[hadoop@server1 hadoop]$ bin/hdfs dfs -ls
Found 1 items
drwxr-xr-x   - hadoop supergroup          0 2019-05-22 22:50 input

删除input和output文件，重新执行命令

[hadoop@server1 hadoop]$ rm -fr input/ output/
[hadoop@server1 hadoop]$ bin/hadoop jar share/hadoop/mapreduce/hadoop-mapreduce-examples-3.0.3.jar grep input output 'dfs[a-z.]+'
[hadoop@server1 hadoop]$ ls
bin  etc  include  lib  libexec  LICENSE.txt  logs  NOTICE.txt  README.txt  sbin  share
**此时input和output不会出现在当前目录下，而是上传到了分布式文件系统中，网页上可以看到**

[hadoop@server1 hadoop]$ bin/hdfs dfs -cat output/*
1	dfsadmin
[hadoop@server1 hadoop]$ bin/hdfs dfs -get output      ##从分布式系统中get下来output目录
[hadoop@server1 hadoop]$ cd output/
[hadoop@server1 output]$ ls
part-r-00000  _SUCCESS
[hadoop@server1 output]$ cat *
1	dfsadmin

三、分布式

1.先停掉服务，清除原来的数据

[hadoop@server1 hadoop]$ sbin/stop-dfs.sh
[hadoop@server1 hadoop]$ jps
13867 Jps
[hadoop@server1 ~]$ cd /tmp
[hadoop@server1 tmp]$ ls
hadoop  hadoop-hadoop  hsperfdata_hadoop
[hadoop@server1 tmp]$ rm -fr *

2.新开两个虚拟机，当做节点

##创建用户
[root@server2 ~]# useradd -u 1000 hadoop
[root@server3 ~]# useradd -u 1000 hadoop

##安装nfs-utils
[root@server1 ~]# yum install -y nfs-utils
[root@server2 ~]# yum install -y nfs-utils
[root@server3 ~]# yum install -y nfs-utils

[root@server1 ~]# systemctl start rpcbind
[root@server2 ~]# systemctl start rpcbind
[root@server3 ~]# systemctl start rpcbind

3.server1开启服务，配置

[root@server1 ~]# systemctl start nfs-server
[root@server1 ~]# vim /etc/exports
/home/hadoop   *(rw,anonuid=1000,anongid=1000)
[root@server1 ~]# exportfs -rv
exporting *:/home/hadoop
[root@server1 ~]# showmount -e
Export list for server1:
/home/hadoop *

4.server2,3挂载

[root@server2 ~]# mount 172.25.26.1:/home/hadoop /home/hadoop
[root@server2 ~]# df
Filesystem               1K-blocks    Used Available Use% Mounted on
/dev/mapper/rhel-root     17811456 1097752  16713704   7% /
devtmpfs                    497292       0    497292   0% /dev
tmpfs                       508264       0    508264   0% /dev/shm
tmpfs                       508264   13128    495136   3% /run
tmpfs                       508264       0    508264   0% /sys/fs/cgroup
/dev/sda1                  1038336  141508    896828  14% /boot
tmpfs                       101656       0    101656   0% /run/user/0
172.25.26.1:/home/hadoop  17811456 2797184  15014272  16% /home/hadoop

[root@server3 ~]# mount 172.25.26.1:/home/hadoop /home/hadoop

5.此时发现可以免密登录（因为是挂载上的）

[root@server1 ~]# su - hadoop
Last login: Sat Apr  6 10:12:17 CST 2019 from localhost on pts/1
[hadoop@server1 ~]$ ssh 172.25.26.2
[hadoop@server2 ~]$ logout
Connection to 172.25.26.2 closed.
[hadoop@server1 ~]$ ssh 172.25.26.3
[hadoop@server3 ~]$ logout
Connection to 172.25.26.3 closed.

6.重新编辑文件

[hadoop@server1 hadoop]$ pwd
/home/hadoop/hadoop/etc/hadoop
[hadoop@server1 hadoop]$ vim core-site.xml 
<configuration>
    <property>
        <name>fs.defaultFS</name>
        <value>hdfs://172.25.26.1:9000</value>
    </property>
</configuration>


[hadoop@server1 hadoop]$ vim hdfs-site.xml 
<configuration>
    <property>
        <name>dfs.replication</name>
        <value>2</value>     ##改为两个节点
    </property>
</configuration>

[hadoop@server1 hadoop]$ vim workers 
[hadoop@server1 hadoop]$ cat workers 
172.25.26.2
172.25.26.3
##在一个地方编辑，其他节点都有了
[root@server2 ~]# su - hadoop
Last login: Sat Apr  6 11:32:41 CST 2019 from server1 on pts/1
[hadoop@server2 ~]$ cd hadoop/etc/hadoop/
[hadoop@server2 hadoop]$ cat workers 
172.25.26.2
172.25.26.3

[root@server3 ~]# su - hadoop
Last login: Sat Apr  6 11:32:41 CST 2019 from server1 on pts/1
[hadoop@server3 ~]$ cd hadoop/etc/hadoop/
[hadoop@server3 hadoop]$ cat workers 
172.25.26.2
172.25.26.3

7.格式化，并启动服务

[hadoop@server1 hadoop]$ bin/hdfs namenode -format
[hadoop@server1 hadoop]$ sbin/start-dfs.sh 
Starting namenodes on [server1]
Starting datanodes
Starting secondary namenodes [server1]

[hadoop@server1 hadoop]$ jps
14085 NameNode
14424 Jps
14303 SecondaryNameNode     ##出现SecondaryNameNode

##从节点可以看到datanode信息
[hadoop@server2 ~]$ jps
11959 DataNode
12046 Jps
[hadoop@server3 ~]$ jps
2616 DataNode
2702 Jps

8.测试

[hadoop@server1 hadoop]$ bin/hdfs dfs -mkdir -p /user/hadoop
[hadoop@server1 hadoop]$ bin/hdfs dfs -mkdir input
[hadoop@server1 hadoop]$ bin/hdfs dfs -put etc/hadoop/*.xml input
[hadoop@server1 hadoop]$ bin/hadoop jar share/hadoop/mapreduce/hadoop-mapreduce-examples-3.0.3.jar grep input output 'dfs[a-z.]+'

网页上查看，有两个节点，且数据已经上传