Hadoop的安装和部署
系统：RedHat linux enterprise5
Jdk：jdk1.6
Hadoop：Hadoop-0.19.2
节点数目：两台（可自行扩充）
转换问root用户，修改/etc/hosts文件，内容如下：
# Do not remove the following line, or various programs
# that require network functionality will fail.
127.0.0.1?????? localhost.localdomain?? localhost
::1???? localhost6.localdomain6 localhost6
192.168.0.121?? hwellzen-bj-1.compute?? hwellzen-bj-1
192.168.0.122?? hwellzen-bj-2.compute?? hwellzen-bj-2
?
注意：以上的内容有回车符的时候才进行换行。将两台机器的hosts都设置问以上的内容，然后分别重启系统。
[liuzj@hwellzen-bj-1 ~]$ssh-keygen? -t? rsa
这个命令将为hwellzen-bj-1上的用户liuzj生成其密钥对，询问其保存路径时直接回车采用默认路径，当提示要为生成的密钥输入passphrase的时候，直接回车，也就是将其设定为空密码。生成的密钥对id_rsa，id_rsa.pub，默认存储在/home/liuzj/.ssh目录下。
执行命令：
cp id_rsa.pub authorized_keys
可以实现用户在本地匿名登录，现象为
[liuzj@hwellzen-bj-1 ~]$ssh hwellzen-bj-1
Last login: Tue Aug 11 09:31:49 2009 from 192.168.0.129
[liuzj@hwellzen-bj-1 ~]$
?
?
?
[liuzj@hwellzen-bj-1 ~]$ssh-keygen? -t? rsa
[liuzj@hwellzen-bj-1 ~]$ scp .ssh/id_rsa.pub hwellzen-bj-2:/home/liuzj
[liuzj@hwellzen-bj-2 ~]$ cat id_rsa.pub >> .ssh/authorized_keys
我这里的现象：
[liuzj@hwellzen-bj-1 ~]$ ssh hwellzen-bj-2
Last login: Tue Aug 11 09:31:49 2009 from 192.168.0.129
[liuzj@hwellzen-bj-2 ~]$
Chmod u+x jdk-6u2-linux-i586.bin
./ jdk-6u2-linux-i586.bin
文件安装完成
PATH=/usr/local/java/jdk1.6.0_02/bin:$PATH
JAVA_HOME=/usr/local/java/jdk1.6.0_02
export PATH JAVA_HOME
source? /etc/profile
执行命令：java version
[liuzj@hwellzen-bj-2 ~]$ java -version
java version "1.6.0_02"
Java(TM) SE Runtime Environment (build 1.6.0_02-b05)
Java HotSpot(TM) Client VM (build 1.6.0_02-b05, mixed mode, sharing)
[liuzj@hwellzen-bj-2 ~]$
?????????????????????
将hadoop-0.19.2.tar.gz解压到，用户liuzj下使用的命令为
[liuzj@hwellzen-bj-2 ~]$ tar zxvf hadoop-0.19.2.tar.gz
最终解压后的目录为：
[liuzj@hwellzen-bj-2 hadoop-0.19.2]$ pwd
/home/liuzj/hadoop-0.19.2
注意:保证各台机器安装的目录机构都是相同的。
需要配置的文件：hadoop-env.sh，slaves，masters，hadoop-site.xml
# The java implementation to use.? Required.
?export JAVA_HOME=/usr/local/java/jdk1.6.0_02
hwellzen-bj-2
hwellzen-bj-1
hwellzen-bj-1
<configuration>
<property>
?? <name>fs.default.name</name>
?? <value>hdfs://hwellzen-bj-1:4310/</value>
</property>
<property>
?? <name>mapred.job.tracker</name>//
?? <value>hdfs://hwellzen-bj-1:4311/</value>
</property>
<property>
?? <name>dfs.replication</name>
?? <value>2</value>
</property>
<property>
??? <name>hadoop.tmp.dir</name>
??? <value>/home/liuzj/hadoop-0.19.2/tmp</value>
</property>
<property>
? <name>dfs.name.dir</name>
? <value>/home/liuzj/hadoop-0.19.2/filesystem/name/</value>
</property>
<property>
? <name>dfs.data.dir</name>
? <value>/opt/hadoop-0.19.2/filesystem/data</value>
? <description>Determines where on the local filesystem an DFS data node should store its blocks. If this is a comma-delimited list of directories, then data will be stored in all named directories, typically on different devices. Directories that do not exist are ignored.</description>
</property>
<property>
?? <name>mapred.child.java.opts</name>
?? <value>-Xmx512m</value>
</property>
</configuration>
格式化dfs：
???????????????????? [liuzj@hwellzen-bj-1 hadoop-0.19.2]$ bin/hadoop namenode -format
?
?
启动hadoop
[liuzj@hwellzen-bj-1 hadoop-0.19.2]$ bin/start-all.sh
访问
?
http://192.168.0.121:50070/dfshealth.jsp
http://192.168.0.121:50030/jobtracker.jsp
?
注意：保证hadoop的需要用的端口都是可以访问的，本人在配置的时候因为防火墙组织了端口的访问造成hadoop的启动失败，后来关闭的防火墙，启动成功。