hadoop 1.00 集群安装（hadoop-2.6.4）

#需要
1. jdk (版本信息 http://wiki.apache.org/hadoop/HadoopJavaVersions） 
2. ssh 无密码登录，包括localhost 和0.0.0.0
3. rsync
***
#安装步骤
（准备了3台机器hadoop1,hadoop2,hadoop3）
mkdir /app/hadoop && cd /app/hadoop
mkdir name && mkdir data && mkdir tmp   #创建namenode文件夹，datanode文件夹，临时文件夹
tar -xzvf ../hadoop-2.6.4.tar.gz
cd hadoop-2.6.4/etc/hadoop
vim core-site.xml
```
<configuration>
<property>
    <name>fs.default.name</name>
    <value>hdfs://hadoop1:9000</value>
</property>
<property>
    <name>hadoop.tmp.dir</name>
    <value>/app/hadoop/tmp</value>
</property>
</configuration>
```
vim hdfs-site.xml
```
<configuration>
<property>
    <name>dfs.replication</name>    # 每个数据几份复制
    <value>1</value>
</property>
<property>
    <name>dfs.namenode.name.dir</name>  #存放namenode 数据的地方
    <value>/app/hadoop/name</value>
</property>
<property>
    <name>dfs.datanode.data.dir</name>  #存放datanode 数据的地方
    <value>/app/hadoop/data</value>
</property>
<property>
    <name>dfs.namenode.checkpoint.period</name>  # 多少时间创建一个检查点
    <value>3600</value>
</property>
<property>
    <name>dfs.namenode.secondary.http-address</name>  #secondarynamenode 是谁
    <value>hadoop2:50090</value>
</property>
</configuration>
```
cp mapred-site.xml.template  mapred-site.xml
vim mapred-site.xml
```
<configuration>
<property>
    <name>mapreduce.framework.name</name>
    <value>yarn</value>
</property>
</configuration>
```
vim yarn-site.xml
```
<configuration>
<property>
    <name>yarn.nodemanager.aux-services</name>
    <value>mapreduce_shuffle</value>   #让yarn管理mapreduce
</property>
<property>
    <name>yarn.resourcemanager.hostname</name>
    <value>hadoop1</value>
</property>
</configuration>
```
vim slaves
```
hadoop1
hadoop2
hadoop3
```
cd /app/hadoop/hadoop-2.6.4/bin/
./hadoop namenode -format           #格式化namenode

cd /app/hadoop/hadoop-2.6.4/sbin/
./start-all.sh                      #start-dfs.sh && start-yarn.sh
***
#初步检查/使用hadoop
##初步检查/使用HDFS
cd /app/hadoop/hadoop-2.6.4/bin/
./hadoop dfsadmin -report           #看看是不是所有的datanode 都起来了

登录图形界面 http://localhost:50070/dfshealth.html

尝试放一点文件进HDFS
```
[hadoop@hadoop1 bin]$ ./hadoop fs -ls /
16/07/03 12:34:22 WARN util.NativeCodeLoader: Unable to load native-hadoop library for your platform... using builtin-java classes where applicable
[hadoop@hadoop1 bin]$ ./hadoop fs -put ~/.bashrc  /
16/07/03 12:34:37 WARN util.NativeCodeLoader: Unable to load native-hadoop library for your platform... using builtin-java classes where applicable
[hadoop@hadoop1 bin]$ ./hadoop fs -ls /
16/07/03 12:34:45 WARN util.NativeCodeLoader: Unable to load native-hadoop library for your platform... using builtin-java classes where applicable
Found 1 items
-rw-r--r--   1 hadoop supergroup        181 2016-07-03 12:34 /.bashrc
[hadoop@hadoop1 bin]$
```
***
##初步检查/使用MapReduce
登录图形界面 http://localhost:8088
放入input文件
```
[hadoop@hadoop1 bin]$ ./hadoop fs -mkdir /input
16/07/03 13:27:26 WARN util.NativeCodeLoader: Unable to load native-hadoop library for your platform... using builtin-java classes where applicable
[hadoop@hadoop1 bin]$ echo 123 > /tmp/a
[hadoop@hadoop1 bin]$ ./hadoop fs -put /tmp/a /input
16/07/03 13:27:57 WARN util.NativeCodeLoader: Unable to load native-hadoop library for your platform... using builtin-java classes where applicable
```
跑job
```
[hadoop@hadoop1 bin]$ ./hadoop jar ../share/hadoop/tools/lib/hadoop-streaming-2.6.4.jar -input /input -output /output1 -mapper /bin/cat -reducer /usr/bin/wc
..........
```

乱读天书， 不求甚解

乱读天书，不求甚解