==== 安装环境 ====

虚拟机：
  * 192.168.0.2   master
  * 192.168.0.3   slave1
  * 192.168.0.4   slave2

  * jave版本："1.7.0_80"  （oracle下载）

  * hadoop版本：2.6 （apache下载）

==== 开始安装 ====
  - 创建一个新用户：<code>useradd hadoop
给hadoop添加sudo
vim /etc/sudoers
hadoop  ALL=(ALL)       NOPASSWD: ALL

sudo chown hadoop:hadoop -R /usr/local
</code>
  - 下载jdk解压到/usr/loacl
  - 下载hadoop解压到/usr/loacl
  - 设置环境变量
    - <code>
export JAVA_HOME=/usr/local/jdk1.7.0_80
export HADOOP_HOME=/usr/local/hadoop-2.6.0
export PATH=$JAVA_HOME/bin/:$HADOOP_HOME/bin:$HADOOP_HOME/sbin:$PATH</code>
  - 无密码登录
    - <code>
ssh-keygen  -t rsa
cat /home/hadoop/.ssh/id_rsa.pub >>/home/hadoop/.ssh/authorized_keys

避免首次询问：Are you sure you want to continue connecting (yes/no)?
vim /etc/ssh/ssh_config
把StrictHostKeyChecking ask 改成 StrictHostKeyChecking no
</code>
  - 设置hostname
    - <code>cat /etc/sysconfig/network
NETWORKING=yes
HOSTNAME=master</code>
  - 设置本地路由,添加如下记录
    - <code>vim /etc/hosts
192.168.0.2 master
192.168.0.3 slave1
192.168.0.4 slave2</code>
  - 禁用selinux<code>vim /etc/selinux/config 
SELINUX=disabled</code>
  - 关闭防火墙<code>service iptables stop
chkconfig iptables off</code>
==== 配置master主机 ====
**core-site.xml**
<code>
<configuration>
        <property>
                <name>fs.defaultFS</name> 
                <value>hdfs://master:9000</value> //NameNode为集群名称 
        </property>
        <property>
                <name>io.file.buffer.size</name>
                <value>131072</value>
        </property>
</configuration>
</code>

**hdfs-site.xml**
<code>
<configuration>
        <property>
                <name>dfs.namenode.name.dir</name>
                <value>file:///usr/local/hadoop_data/dfs/name</value> //NameNode节点目录 ,需要提前创建，并可写权限，如果目录不存在，会忽略此配置
        </property>
         <property>
                <name>dfs.datanode.data.dir</name>
                <value>file:///usr/local/hadoop_data/dfs/data</value> //DataNode节点目录  ,需要提前创建，并可写权限，如果目录不存在，会忽略此配置
        </property>


</configuration>
</code>


**yarn-site.xml**
<code>
<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>
</configuration>
</code>

**mapred-site.xml**
<code>
<configuration>
        <property>
                <name>mapreduce.framework.name</name> 
                <value>yarn</value>  //mapreduce的frmawork指定为yarn
                <description>Execution framework set to Hadoop YARN.</description>
        </property>
</configuration>
</code>

**slaves**
<code>
slave1
slave2
</code>
==== 配置slave主机====
  * 配置和master大致一样，不同点如下
    - 主机名不同
    - ip不同

如果是用虚拟机搭建测试环境的话，配置号master然后克隆2个slave1改改就好了

==== 启动hadoop ====
  * hdfs namenode -format master   #master节点格式化hdfs
  * start-dfs.sh
  * start-yarn.sh
  * jps 查看启动进程

<code>
web 查看状态
http://master:8088
http://master:50070
http://master:50070
</code>
==== 测试 ====
**hadoop自带的例子**
<code>
hadoop jar /usr/local/hadoop-2.6.0/share/hadoop/mapreduce/hadoop-mapreduce-examples-2.6.0.jar wordcount /input /output
</code>
**自己编译hadoop程序**
<code>
hadoop fs -rmr /input
hadoop fs -rmr /output
hadoop fs -rmr /tmp
hadoop fs - input.txt  /input/
echo "hello word" > input.txt
hadoop fs -mkdir /input
hadoop fs -put input.txt  /input/
rm -rf input.txt
# 指定编译依赖的jar包，WordCount.java中的代码百度搜索即可
javac -classpath $HADOOP_HOME/share/hadoop/common/lib/commons-cli-1.2.jar:$HADOOP_HOME/share/hadoop/mapreduce/hadoop-mapreduce-client-core-2.6.0.jar:$HADOOP_HOME/share/hadoop/common/hadoop-common-2.6.0.jar WordCount.java
jar cf wc.jar WordCount*.class
hdfs dfs -rmr /out*
hadoop jar wc.jar WordCount /input /output
</code>