Hadoop的运行模式可分为单机模式、伪分布模式和分布模式。
首先无论哪种模式都需要安装JDK的，这一步之前的随笔Ubuntu 14.04 LTE下安装JDK 1.8中已经做了。这里就不多说了。
其次是安装SSH。安装SSH是为了每次可以免密码登陆数据节点服务器。因为集群的环境下，每次登陆到数据节点服务器不可能每次都输入密码。这一步在前面的随笔Ubuntu 14.04 LTE下配置SSH免密码登录中已经做了。这里也不多说了。
伪分布模式安装：
首先下载Hadoop 1.2.1到本机，再解压到用户目录下。
jerry@ubuntu:~/Downloads$ tar zxf hadoop-1.2.1.tar.gz -C ~/hadoop_1.2.1
jerry@ubuntu:~/Downloads$ cd ~/hadoop_1.2.1/
jerry@ubuntu:~/hadoop_1.2.1$ ls
hadoop-1.2.1
jerry@ubuntu:~/hadoop_1.2.1$ cd hadoop-1.2.1/
jerry@ubuntu:~/hadoop_1.2.1/hadoop-1.2.1$ ls
bin hadoop-ant-1.2.1.jar ivy sbin
build.xml hadoop-client-1.2.1.jar ivy.xml share
c++ hadoop-core-1.2.1.jar lib src
CHANGES.txt hadoop-examples-1.2.1.jar libexec webapps
conf hadoop-minicluster-1.2.1.jar LICENSE.txt
contrib hadoop-test-1.2.1.jar NOTICE.txt
docs hadoop-tools-1.2.1.jar README.txt
然后配置hadoop的几个配置文件，都是XML格式。
首先是core-default.xml。这里配置hadoop分布式文件系统的地址和端口，以及Hadoop临时文件目录（/tmp/hadoop-${user.name}）。
jerry@ubuntu:~/hadoop_1.2.1/hadoop-1.2./conf$ cat core-site.xml
<?xml version="1.0"?>
<?xml-stylesheet type="text/xsl" href="configuration.xsl"?> <!-- Put site-specific property overrides in this file. --> <configuration>
<property>
<name>fs.default.name</name>
<value>hdfs://localhost:9000</value>
</property>
<property>
<name>hadoop.tmp.dir</name>
<value>/hadoop/hadooptmp</value>
</property>
</configuration>
jerry@ubuntu:~/hadoop_1.2.1/hadoop-1.2./conf$
修改hadoop系统环境配置文件，告诉hadoop安装好的jdk的主目录路径
jerry@ubuntu:~/hadoop_1.2.1/hadoop-1.2.$ cd conf/
jerry@ubuntu:~/hadoop_1.2.1/hadoop-1.2./conf$ ls
capacity-scheduler.xml hadoop-policy.xml slaves
configuration.xsl hdfs-site.xml ssl-client.xml.example
core-site.xml log4j.properties ssl-server.xml.example
fair-scheduler.xml mapred-queue-acls.xml taskcontroller.cfg
hadoop-env.sh mapred-site.xml task-log4j.properties
hadoop-metrics2.properties masters
jerry@ubuntu:~/hadoop_1.2.1/hadoop-1.2./conf$ sudo vim hadoop-env.sh n
[sudo] password for jerry:
files to edit
jerry@ubuntu:~/hadoop_1.2.1/hadoop-1.2./conf$ sudo vim hadoop-env.sh
jerry@ubuntu:~/hadoop_1.2.1/hadoop-1.2./conf$ tail -n hadoop-env.sh
export JAVA_HOME=/usr/lib/jvm/jdk
然后是hdfs-site.xml 。修改hdfs的文件备份数量为1，dfs命名节点的主目录，dfs数据节点的目录。
jerry@ubuntu:~/hadoop_1.2.1/hadoop-1.2./conf$ cat hdfs-site.xml
<?xml version="1.0"?>
<?xml-stylesheet type="text/xsl" href="configuration.xsl"?> <!-- Put site-specific property overrides in this file. --> <configuration>
<property>
<name>dfs.replication</name>
<value></value>
</property>
<property>
<name>dfs.name.dir</name>
<value>/hadoop/hdfs/name</value>
</property>
<property>
<name>dfs.data.dir</name>
<value>/hadoop/hdfs/data</value>
</property>
</configuration>
jerry@ubuntu:~/hadoop_1.2.1/hadoop-1.2./conf$
最后配置mapreduce的job tracker的地址和端口
jerry@ubuntu:~/hadoop_1.2.1/hadoop-1.2.1/conf$ cat mapred-site.xml
<?xml version="1.0"?>
<?xml-stylesheet type="text/xsl" href="configuration.xsl"?>
<!-- Put site-specific property overrides in this file. -->
<configuration>
<property>
<name>mapred.job.tracker</name>
<value>localhost:9001</value>
</property>
</configuration>
jerry@ubuntu:~/hadoop_1.2.1/hadoop-1.2.1/conf$
配置masters文件和slaves文件，这里因为我们是伪分布式，命名节点和数据节点其实都是一样。
jerry@ubuntu:~/hadoop_1.2.1/hadoop-1.2./conf$ cat masters
localhost
192.168.2.100 jerry@ubuntu:~/hadoop_1.2.1/hadoop-1.2./conf$ cat slaves
localhost
192.168.2.100
jerry@ubuntu:~/hadoop_1.2.1/hadoop-1.2./conf$
编辑/etc/hosts文件，配置主机名和IP地址的映射关系
jerry@ubuntu:~/hadoop_1.2.1/hadoop-1.2./conf$ cat /etc/hosts
127.0.0.1 localhost
127.0.1.1 ubuntu # The following lines are desirable for IPv6 capable hosts
:: ip6-localhost ip6-loopback
fe00:: ip6-localnet
ff00:: ip6-mcastprefix
ff02:: ip6-allnodes
ff02:: ip6-allrouters
192.168.2.100 master
192.168.2.100 slave
jerry@ubuntu:~/hadoop_1.2.1/hadoop-1.2./conf$
创建好core-default.xml，hdfs-site.xml，mapred-site.xml 三个配置文件里面写到的目录
jerry@ubuntu:~/hadoop_1.2.1/hadoop-1.2./conf$ mkdir -p /hadoop/hadooptmp
jerry@ubuntu:~/hadoop_1.2.1/hadoop-1.2./conf$ mkdir -p /hadoop/hdfs/name
jerry@ubuntu:~/hadoop_1.2.1/hadoop-1.2./conf$ mkdir -p /hadoop/hdfs/data
格式化HDFS
jerry@ubuntu:~/hadoop_1.2.1/hadoop-1.2./bin$ ./hadoop namenode -format
启动所有Hadoop服务，包括JobTracker，TaskTracker，Namenode
jerry@ubuntu:~/hadoop_1.2.1/hadoop-1.2./bin$ ./start-all.sh
starting namenode, logging to /home/jerry/hadoop_1.2.1/hadoop-1.2./libexec/../logs/hadoop-jerry-namenode-ubuntu.out
192.168.68.130: starting datanode, logging to /home/jerry/hadoop_1.2.1/hadoop-1.2./libexec/../logs/hadoop-jerry-datanode-ubuntu.out
localhost: starting datanode, logging to /home/jerry/hadoop_1.2.1/hadoop-1.2./libexec/../logs/hadoop-jerry-datanode-ubuntu.out
localhost: ulimit -a for user jerry
localhost: core file size (blocks, -c)
localhost: data seg size (kbytes, -d) unlimited
localhost: scheduling priority (-e)
localhost: file size (blocks, -f) unlimited
localhost: pending signals (-i)
localhost: max locked memory (kbytes, -l)
localhost: max memory size (kbytes, -m) unlimited
localhost: open files (-n)
localhost: pipe size ( bytes, -p)
localhost: starting secondarynamenode, logging to /home/jerry/hadoop_1.2.1/hadoop-1.2./libexec/../logs/hadoop-jerry-secondarynamenode-ubuntu.out
192.168.68.130: secondarynamenode running as process . Stop it first.
starting jobtracker, logging to /home/jerry/hadoop_1.2.1/hadoop-1.2./libexec/../logs/hadoop-jerry-jobtracker-ubuntu.out
192.168.68.130: starting tasktracker, logging to /home/jerry/hadoop_1.2.1/hadoop-1.2./libexec/../logs/hadoop-jerry-tasktracker-ubuntu.out
localhost: starting tasktracker, logging to /home/jerry/hadoop_1.2.1/hadoop-1.2./libexec/../logs/hadoop-jerry-tasktracker-ubuntu.out
localhost: ulimit -a for user jerry
localhost: core file size (blocks, -c)
localhost: data seg size (kbytes, -d) unlimited
localhost: scheduling priority (-e)
localhost: file size (blocks, -f) unlimited
localhost: pending signals (-i)
localhost: max locked memory (kbytes, -l)
localhost: max memory size (kbytes, -m) unlimited
localhost: open files (-n)
localhost: pipe size ( bytes, -p)
jerry@ubuntu:~/hadoop_1.2.1/hadoop-1.2./bin$
查看Hadoop服务是否启动成功
jerry@ubuntu:~/hadoop_1.2.1/hadoop-1.2.1/conf$ jps
3472 JobTracker
3604 TaskTracker
3084 NameNode
5550 Jps
3247 DataNode
3391 SecondaryNameNode
jerry@ubuntu:~/hadoop_1.2.1/hadoop-1.2.1/conf$
查看hadoop群集的状态
jerry@ubuntu:~/hadoop_1.2.1/hadoop-1.2./bin$ ./hadoop dfsadmin -report
Configured Capacity: (38.26 GB)
Present Capacity: (30.48 GB)
DFS Remaining: (30.48 GB)
DFS Used: ( KB)
DFS Used%: %
Under replicated blocks:
Blocks with corrupt replicas:
Missing blocks: -------------------------------------------------
Datanodes available: ( total, dead) Name: 127.0.0.1:
Decommission Status : Normal
Configured Capacity: (38.26 GB)
DFS Used: ( KB)
Non DFS Used: (7.79 GB)
DFS Remaining: (30.48 GB)
DFS Used%: %
DFS Remaining%: 79.65%
Last contact: Sat Dec :: PST jerry@ubuntu:~/hadoop_1.2.1/hadoop-1.2./bin$
过程中遇到不少问题，这里贴下一些有用的链接：