1.安装前，准备三台CENTOS 6.6系统的主机或虚机,并且关闭防火墙及selinux.
192.168.199.21hadoop21 Master
102.168.199.22hadoop22 Slave1
192.168.199.23hadoop23 Slave2
同理修改Slave1，Slave2的IP地址，hosts文件及本机名。
3.安装ORACLE JDK
先卸载本机openJDK,使用rpm -qa|grep java查看，然后用rpm -e 卸载
从oracle网站找到最新JDK,我这选择了JDK8
http://www.oracle.com/technetwork/java/javase/downloads/jdk8-downloads-2133151.html
下载好以后解压，并移至/usr/java,如果没有可以mkdir 建立。
tar -xzvfjdk-8u51-linux-x64.gz
mvjdk1.8.0_51 /usr/java
vi /etc/profile
export JAVA_HOME=/usr/java/jdk1.8.0_51
export CLASSPATH=.:$JAVA_HOME/lib/rt.jar:$JAVA_HOME/lib/dt.jar:$JAVA_HOME/lib/tools.jar
export PATH=$PATH:$JAVA_HOME/bin
source /etc/profile
4.在各节点分别建立Hadoop运行帐号grid,并设置密码
5.配置SSH免密码登陆。
在各节点分别以grid用户名生成两个密钥文件，一个是私钥id_rsa,另一个是公钥id_rsa.pub
ssh-keygen -t rsa -f ~/.ssh/id_rsa
然后在hadoop21上
cp /home/grid/.ssh/id_rsa.pub /home/grid/.ssh/authorized_keys
scp hadoop22:/home/grid/.ssh/id_rsa.pub pubkeys22
scp hadoop23:/home/grid/.ssh/id_rsa.pub pubkeys23
cat pubkeys22 >> /home/grid/.ssh/authorized_keys
cat pubkeys23 >> /home/grid/.ssh/authorized_keys
rm pubkeys22
rm pubkeys23
最后分发authorized_keys到各节点
scp /home/grid/.ssh/authorized_keys hadoop22:/home/grid/.ssh
scp /home/grid/.ssh/authorized_keys hadoop23:/home/grid/.ssh
6.在Master机下载并解压Hadoop2.7.1（使用grid用户名)
找到最近的hadoop镜像，使用wget下载2.7.1
wget http://mirror.bit.edu.cn/apache/hadoop/common/hadoop-2.7.1/hadoop-2.7.1.tar.gz
解压hadoop-2.7.1.tar.gz
tar -xzvfhadoop-2.7.1.tar.gz
cd hadoop-2.7.1
建立tmp,dfs,dfs/data,dfs/name
修改hadoop-env.sh
export JAVA_HOME=/usr/java/jdk1.8.0_51
8. 分发至各Salve节点
scp -r /home/grid/hadoop-2.7.1 hadoop22:/home/grid
scp -r /home/grid/hadoop-2.7.1 hadoop23:/home/grid
9.Master机格式化namenode
cd /home/grid/hadoop-2.7.1
./bin/hdfs namenode -format
10.启动Hadoop
11.验证是否成功
Master机应该启动NameNode,SecondaryNameNode,ResourceManager
Slave机应该启动Datanode,NodeManager
