【hadoop2.6.0】安装+例子运行

由于下载的是hadoop的最新版，网上各种杂七杂八的东西都不适用。好在官网上说的也够清楚了。如果有人看这篇文章的话，最大的忠告就是看官网。

官网2.6.0的安装教程：http://hadoop.apache.org/docs/r2.6.0/hadoop-project-dist/hadoop-common/SingleCluster.html

hdfs指令：http://hadoop.apache.org/docs/r2.6.0/hadoop-project-dist/hadoop-common/FileSystemShell.html

注意：2.6.0默认的都是64位系统的，如果用32位的机器总是会出现下面的警告： 这个可以无视，不会影响结果

Java HotSpot(TM) Client VM warning: You have loaded library /home/software/hadoop-2.6.0/lib/native/libhadoop.so.1.0.0 which might have disabled stack guard. The VM will try to fix the stack guard now.
It‘s highly recommended that you fix the library with ‘execstack -c <libfile>‘, or link it with ‘-z noexecstack‘.
14/12/04 21:52:59 WARN util.NativeCodeLoader: Unable to load native-hadoop library for your platform... using builtin-java classes where applicable

1.安装jdk 我写在另一篇文章里了http://www.cnblogs.com/dplearning/p/4140334.html

2. ssh免密码登陆 http://www.cnblogs.com/dplearning/p/4140352.html

3.配置

etc/hadoop/core-site.xml:

<configuration>
    <property>
        <name>fs.defaultFS</name>
        <value>hdfs://localhost:9000</value>
    </property>
</configuration>

etc/hadoop/hdfs-site.xml:

<configuration>
    <property>
        <name>dfs.replication</name>
        <value>1</value>
    </property>
</configuration>

4.  $ bin/hdfs namenode -format   //格式化

5.  $ sbin/start-dfs.sh //开启进程

成功的话，jps查看进程应该是

如果没有DataNode 查看一下日志

如果有错误

java.io.IOException: Incompatible clusterIDs in /tmp/hadoop-root/dfs/data: namenode clusterID = CID-2b67ec7b-5edc-4911-bb22-1bb8092a7613; datanode clusterID = CID-aa4ac802-100d-4d29-813d-c6b92dd78f02

那么，应该是/tmp/hadoop-root 文件夹中还有之前残留的文件，全部清空后重新format，重新启动程序应该就好了。

运行例子：

1.先在hdfs上建个文件夹  bin/hdfs dfs -mkdir -p /user/kzy/input

bin/hdfs dfs -mkdir -p /user/kzy/output

2.先上传一些文件：bin/hdfs dfs -put etc/hadoop/ /user/kzy/input  把etc/hadoop文件上传到hdfs的/user/kzy/input中

3.执行指令

bin/hadoop jar share/hadoop/mapreduce/hadoop-mapreduce-examples-2.6.0.jar grep /user/kzy/input/hadoop /user/kzy/output/o ‘dfs[a-z.]+‘

注意/user/kzy/output/o 是个没有建立过的文件夹，如果用已有的文件夹会有个警告

4.查看结果

bin/hdfs dfs -cat /user/kzy/output/o/*

再运行一些wordcount,官网的在http://hadoop.apache.org/docs/r2.6.0/hadoop-mapreduce-client/hadoop-mapreduce-client-core/MapReduceTutorial.html#Example:_WordCount_v1.0

运行

bin/hadoop jar share/hadoop/mapreduce/hadoop-mapreduce-examples-2.6.0.jar wordcount /user/kzy/input/hadoop /user/kzy/output/wordcount

用

bin/hdfs dfs -cat /user/kzy/output/wordcount/*   看结果