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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 LTS 下安装 JDK 1.8 中已经做了(见 http://www.linuxidc.com/Linux/2016-09/135403.htm)。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 LTS 下配置 SSH 免密码登录中已经做了（见 http://www.linuxidc.com/Linux/2016-09/135404.htm）。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。
linuxidc@ubuntu:~/Downloads$ tar zxf hadoop-1.2.1.tar.gz -C ~/hadoop_1.2.1
linuxidc@ubuntu:~/Downloads$ cd ~/hadoop_1.2.1/
linuxidc@ubuntu:~/hadoop_1.2.1$ ls
hadoop-1.2.1
linuxidc@ubuntu:~/hadoop_1.2.1$ cd hadoop-1.2.1/
linuxidc@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-${user.name}）。
linuxidc@ubuntu:~/hadoop_1.2.1/hadoop-1.2.1/conf$ cat core-site.xml
<?xml version=”1.0″?>
<?xml-stylesheet type=”text/xsl” href=”https://www.linuxidc.com/Linux/2016-09/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>
linuxidc@ubuntu:~/hadoop_1.2.1/hadoop-1.2.1/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
linuxidc@ubuntu:~/hadoop_1.2.1/hadoop-1.2.1$ cd conf/
linuxidc@ubuntu:~/hadoop_1.2.1/hadoop-1.2.1/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
linuxidc@ubuntu:~/hadoop_1.2.1/hadoop-1.2.1/conf$ sudo vim hadoop-env.sh n
[sudo] password for linuxidc:
2 files to edit
linuxidc@ubuntu:~/hadoop_1.2.1/hadoop-1.2.1/conf$ sudo vim hadoop-env.sh
linuxidc@ubuntu:~/hadoop_1.2.1/hadoop-1.2.1/conf$ tail -n 1 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。
linuxidc@ubuntu:~/hadoop_1.2.1/hadoop-1.2.1/conf$ cat hdfs-site.xml
<?xml version=”1.0″?>
<?xml-stylesheet type=”text/xsl” href=”https://www.linuxidc.com/Linux/2016-09/configuration.xsl”?>
<!– Put site-specific property overrides in this file. –>
<configuration>
<property>
<name>dfs.replication</name>
<value>1</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>
linuxidc@ubuntu:~/hadoop_1.2.1/hadoop-1.2.1/conf$
最后配置 mapreduce 的 job tracker 的地址和端口
linuxidc@ubuntu:~/hadoop_1.2.1/hadoop-1.2.1/conf$ cat mapred-site.xml
<?xml version=”1.0″?>
<?xml-stylesheet type=”text/xsl” href=”https://www.linuxidc.com/Linux/2016-09/configuration.xsl”?>
<!– Put site-specific property overrides in this file. –>
<configuration>
<property>
<name>mapred.job.tracker</name>
<value>localhost:9001</value>
</property>
</configuration>
linuxidc@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。
linuxidc@ubuntu:~/hadoop_1.2.1/hadoop-1.2.1/conf$ cat masters
localhost
192.168.2.100
linuxidc@ubuntu:~/hadoop_1.2.1/hadoop-1.2.1/conf$ cat slaves
localhost
192.168.2.100
linuxidc@ubuntu:~/hadoop_1.2.1/hadoop-1.2.1/conf$
编辑 /etc/hosts 文件，配置主机名和 IP 地址的映射关系
linuxidc@ubuntu:~/hadoop_1.2.1/hadoop-1.2.1/conf$ cat /etc/hosts
127.0.0.1 localhost
127.0.1.1 ubuntu
# The following lines are desirable for IPv6 capable hosts
::1 ip6-localhost ip6-loopback
fe00::0 ip6-localnet
ff00::0 ip6-mcastprefix
ff02::1 ip6-allnodes
ff02::2 ip6-allrouters
192.168.2.100 master
192.168.2.100 slave
linuxidc@ubuntu:~/hadoop_1.2.1/hadoop-1.2.1/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
linuxidc@ubuntu:~/hadoop_1.2.1/hadoop-1.2.1/conf$ mkdir -p /hadoop/hadooptmp
linuxidc@ubuntu:~/hadoop_1.2.1/hadoop-1.2.1/conf$ mkdir -p /hadoop/hdfs/name
linuxidc@ubuntu:~/hadoop_1.2.1/hadoop-1.2.1/conf$ mkdir -p /hadoop/hdfs/data
格式化 HDFS
linuxidc@ubuntu:~/hadoop_1.2.1/hadoop-1.2.1/bin$ ./hadoop namenode -format
启动所有 Hadoop 服务，包括 JobTracker，TaskTracker，Namenode
linuxidc@ubuntu:~/hadoop_1.2.1/hadoop-1.2.1/bin$ ./start-all.sh
starting namenode, logging to /home/linuxidc/hadoop_1.2.1/hadoop-1.2.1/libexec/../logs/hadoop-linuxidc-namenode-ubuntu.out
192.168.68.130: starting datanode, logging to /home/linuxidc/hadoop_1.2.1/hadoop-1.2.1/libexec/../logs/hadoop-linuxidc-datanode-ubuntu.out
localhost: starting datanode, logging to /home/linuxidc/hadoop_1.2.1/hadoop-1.2.1/libexec/../logs/hadoop-linuxidc-datanode-ubuntu.out
localhost: ulimit -a for user linuxidc
localhost: core file size (blocks, -c) 0
localhost: data seg size (kbytes, -d) unlimited
localhost: scheduling priority (-e) 0
localhost: file size (blocks, -f) unlimited
localhost: pending signals (-i) 7855
localhost: max locked memory (kbytes, -l) 64
localhost: max memory size (kbytes, -m) unlimited
localhost: open files (-n) 1024
localhost: pipe size (512 bytes, -p) 8
localhost: starting secondarynamenode, logging to /home/linuxidc/hadoop_1.2.1/hadoop-1.2.1/libexec/../logs/hadoop-linuxidc-secondarynamenode-ubuntu.out
192.168.68.130: secondarynamenode running as process 10689. Stop it first.
starting jobtracker, logging to /home/linuxidc/hadoop_1.2.1/hadoop-1.2.1/libexec/../logs/hadoop-linuxidc-jobtracker-ubuntu.out
192.168.68.130: starting tasktracker, logging to /home/linuxidc/hadoop_1.2.1/hadoop-1.2.1/libexec/../logs/hadoop-linuxidc-tasktracker-ubuntu.out
localhost: starting tasktracker, logging to /home/linuxidc/hadoop_1.2.1/hadoop-1.2.1/libexec/../logs/hadoop-linuxidc-tasktracker-ubuntu.out
localhost: ulimit -a for user linuxidc
localhost: core file size (blocks, -c) 0
localhost: data seg size (kbytes, -d) unlimited
localhost: scheduling priority (-e) 0
localhost: file size (blocks, -f) unlimited
localhost: pending signals (-i) 7855
localhost: max locked memory (kbytes, -l) 64
localhost: max memory size (kbytes, -m) unlimited
localhost: open files (-n) 1024
localhost: pipe size (512 bytes, -p) 8
linuxidc@ubuntu:~/hadoop_1.2.1/hadoop-1.2.1/bin$
查看 Hadoop 服务是否启动成功
linuxidc@ubuntu:~/hadoop_1.2.1/hadoop-1.2.1/conf$ jps
3472 JobTracker
3604 TaskTracker
3084 NameNode
5550 Jps
3247 DataNode
3391 SecondaryNameNode
linuxidc@ubuntu:~/hadoop_1.2.1/hadoop-1.2.1/conf$
查看 hadoop 群集的状态
linuxidc@ubuntu:~/hadoop_1.2.1/hadoop-1.2.1/bin$ ./hadoop dfsadmin -report
Configured Capacity: 41083600896 (38.26 GB)
Present Capacity: 32723169280 (30.48 GB)
DFS Remaining: 32723128320 (30.48 GB)
DFS Used: 40960 (40 KB)
DFS Used%: 0%
Under replicated blocks: 0
Blocks with corrupt replicas: 0
Missing blocks: 0
————————————————-
Datanodes available: 1 (1 total, 0 dead)
Name: 127.0.0.1:50010
Decommission Status : Normal
Configured Capacity: 41083600896 (38.26 GB)
DFS Used: 40960 (40 KB)
Non DFS Used: 8360431616 (7.79 GB)
DFS Remaining: 32723128320(30.48 GB)
DFS Used%: 0%
DFS Remaining%: 79.65%
Last contact: Sat Dec 26 12:22:07 PST 2015
linuxidc@ubuntu:~/hadoop_1.2.1/hadoop-1.2.1/bin$
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Ubuntu 13.04 上搭建 Hadoop 环境 http://www.linuxidc.com/Linux/2013-06/86106.htm
Ubuntu 12.10 +Hadoop 1.2.1 版本集群配置 http://www.linuxidc.com/Linux/2013-09/90600.htm
Ubuntu 上搭建 Hadoop 环境（单机模式 + 伪分布模式）http://www.linuxidc.com/Linux/2013-01/77681.htm
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更多 Hadoop 相关信息见Hadoop 专题页面 http://www.linuxidc.com/topicnews.aspx?tid=13
本文永久更新链接地址：http://www.linuxidc.com/Linux/2016-09/135406.htm
