1.Hadoop的节点构成如下：
HDFS daemon： NameNode, SecondaryNameNode, DataNode
YARN damones： ResourceManager, NodeManager, WebAppProxy
MapReduce Job History Server
本次测试的分布式环境为：Master 1台 (test166)，Slave 1台(test167)
2.1 安装JDK及下载解压hadoop
JDK安装可参考： 或 CentOS7.2安装JDK1.7
从官网下载Hadoop最新版2.7.5
[hadoop@hadoop-master ~]$ su - hadoop
[hadoop@hadoop-master ~]$ cd /usr/hadoop/
[hadoop@hadoop-master ~]$ wget
将hadoop解压到/usr/hadoop/下
[hadoop@hadoop-master ~]$ tar zxvf /root/hadoop-2.7.5.tar.gz
结果：
[hadoop@hadoop-master ~]$ ll
total 211852
drwxr-xr-x. 2 hadoop hadoop 6 Jan 31 23:41 Desktop
drwxr-xr-x. 2 hadoop hadoop 6 Jan 31 23:41 Documents
drwxr-xr-x. 2 hadoop hadoop 6 Jan 31 23:41 Downloads
drwxr-xr-x. 10 hadoop hadoop 4096 Feb 22 01:36 hadoop-2.7.5
-rw-rw-r--. 1 hadoop hadoop 216929574 Dec 16 12:03 hadoop-2.7.5.tar.gz
drwxr-xr-x. 2 hadoop hadoop 6 Jan 31 23:41 Music
drwxr-xr-x. 2 hadoop hadoop 6 Jan 31 23:41 Pictures
drwxr-xr-x. 2 hadoop hadoop 6 Jan 31 23:41 Public
drwxr-xr-x. 2 hadoop hadoop 6 Jan 31 23:41 Templates
drwxr-xr-x. 2 hadoop hadoop 6 Jan 31 23:41 Videos
[hadoop@hadoop-master ~]$
2.2 在各节点上设置主机名及创建hadoop组和用户
所有节点（master,slave）
1 [root@hadoop-master ~]# su - root
2 [root@hadoop-master ~]# vi /etc/hosts
3 10.86.255.166 hadoop-master
4 10.86.255.167 slave1
5 注意：修改hosts中，是立即生效的，无需source或者. 。
先使用
建立hadoop用户组
新建用户，useradd -d /usr/hadoop -g hadoop -m hadoop （新建用户hadoop指定用户主目录/usr/hadoop 及所属组hadoop）
passwd hadoop 设置hadoop密码（这里设置密码为hadoop）
[root@hadoop-master ~]# groupadd hadoop
[root@hadoop-master ~]# useradd -d /usr/hadoop -g hadoop -m hadoop
[root@hadoop-master ~]# passwd hadoop
2.3 在各节点上设置SSH无密码登录
最终达到目的：即在master:节点执行 ssh hadoop@salve1不需要密码，此处只需配置master访问slave1免密。
su - hadoop
进入~/.ssh目录
执行：ssh-keygen -t rsa，一路回车
生成两个文件，一个私钥，一个公钥，在master1中执行：cp id_rsa.pub authorized_keys
[hadoop@hadoop-master ~]$ su - hadoop
[hadoop@hadoop-master ~]$ pwd
/usr/hadoop
[hadoop@hadoop-master ~]$ cd .ssh
[hadoop@hadoop-master .ssh]$ ssh-keygen -t rsa
Generating public/private rsa key pair.
Enter file in which to save the key (/usr/hadoop/.ssh/id_rsa):
Enter passphrase (empty for no passphrase):
Enter same passphrase again:
Your identification has been saved in /usr/hadoop/.ssh/id_rsa.
Your public key has been saved in /usr/hadoop/.ssh/id_rsa.pub.
The key fingerprint is:
11:b2:23:8c:e7:32:1d:4c:2f:00:32:1a:15:43:bb:de hadoop@hadoop-master
The key's randomart image is:
+--[ RSA 2048]----+
|=+*.. . . |
|oo O . o . |
|. o B + . |
| = + . . |
| + o S |
| . + |
| . E |
| |
| |
+-----------------+
[hadoop@hadoop-master .ssh]$
[hadoop@hadoop-master .ssh]$ cp id_rsa.pub authorized_keys
[hadoop@hadoop-master .ssh]$ ll
total 16
-rwx------. 1 hadoop hadoop 1230 Jan 31 23:27 authorized_keys
-rwx------. 1 hadoop hadoop 1675 Feb 23 19:07 id_rsa
-rwx------. 1 hadoop hadoop 402 Feb 23 19:07 id_rsa.pub
-rwx------. 1 hadoop hadoop 874 Feb 13 19:40 known_hosts
[hadoop@hadoop-master .ssh]$
2.3.1：本机无密钥登录
[hadoop@hadoop-master ~]$ pwd
/usr/hadoop
[hadoop@hadoop-master ~]$ chmod -R 700 .ssh
[hadoop@hadoop-master ~]$ cd .ssh
[hadoop@hadoop-master .ssh]$ chmod 600 authorized_keys
[hadoop@hadoop-master .ssh]$ ll
total 16
-rwx------. 1 hadoop hadoop 1230 Jan 31 23:27 authorized_keys
-rwx------. 1 hadoop hadoop 1679 Jan 31 23:26 id_rsa
-rwx------. 1 hadoop hadoop 410 Jan 31 23:26 id_rsa.pub
-rwx------. 1 hadoop hadoop 874 Feb 13 19:40 known_hosts
验证：
没有提示输入密码则表示本机无密钥登录成功，如果此步不成功，后续启动hdfs脚本会要求输入密码
[hadoop@hadoop-master ~]$ ssh hadoop@hadoop-master
Last login: Fri Feb 23 18:54:59 2018 from hadoop-master
[hadoop@hadoop-master ~]$
2.3.2：master与其他节点无密钥登录