Hadoop，
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<!-- Put site-specific property overrides in this file. -->
<configuration>
<property>
<name>dfs.name.dir</name>
<value>/root/hadoop/dfs/name</value>
<description>Path on the local filesystem where theNameNode stores the namespace and transactions logs persistently.</description>
</property>
<property>
<name>dfs.data.dir</name>
<value>/root/hadoop/dfs/data</value>
<description>Comma separated list of paths on the localfilesystem of a DataNode where it should store its blocks.</description>
</property>
<property>
<name>dfs.replication</name>
<value>4</value>
</property>
<property>
<name>dfs.permissions</name>
<value>false</value>
<description>need not permissions</description>
</property>
<property>
<name>heartbeat.recheck.interval</name>
<value>5000</value>
</property>
<property>
<name>dfs.heartbeat.interval</name>
<value>2</value>
</property>
</configuration>
1. Hadoop集群安装
6.1在opt目录下新建一个名字为hadoop的目录，将解压后的hadoop-2.8.2文件夹放进该目录下
6.2
新建几个目录
在/root目录下新建几个目录，复制粘贴执行下面的命令：
[root@Master ~]# mkdir /root/hadoop
[root@Master ~]# mkdir /root/hadoop/tmp
[root@Master ~]# mkdir /root/hadoop/var
[root@Master ~]# mkdir /root/hadoop/dfs
[root@Master ~]# mkdir /root/hadoop/dfs/name
[root@Master ~]# mkdir /root/hadoop/dfs/data
6.3 修改etc/hadoop中的一系列配置文件
修改/opt/hadoop/hadoop-2.8.0/etc/hadoop目录内的一系列文件。
A.修改core-site.xml
<configuration>
<property>
<name>hadoop.tmp.dir</name>
<value>/root/hadoop/tmp</value>
<description>Abase for other temporary directories.</description>
</property>
<property>
<name>fs.default.name</name>
<value>hdfs://192.168.137.94:9000</value>
</property>
</configuration>
B. 修改hadoop-env.sh
修改/opt/hadoop/hadoop-2.8.0/etc/hadoop/hadoop-env.sh文件
将export JAVA_HOME=${JAVA_HOME}
修改为：
export JAVA_HOME=/usr/java/jdk1.7.0_79
说明：修改为自己的JDK路径
C. 修改hdfs-site.xml
修改/opt/hadoop/hadoop-2.8.0/etc/hadoop/hdfs-site.xml文件
在<configuration>节点内加入配置:
<property>
<name>dfs.name.dir</name>
<value>/root/hadoop/dfs/name</value>
<description>Path on the local filesystem where theNameNode stores the namespace and transactions logs persistently.</description>
</property>
<property>
<name>dfs.data.dir</name>
<value>/root/hadoop/dfs/data</value>
<description>Comma separated list of paths on the localfilesystem of a DataNode where it should store its blocks.</description>
</property>
<property>
<name>dfs.replication</name>
<value>2</value>
</property>
<property>
<name>dfs.permissions</name>
<value>false</value>
<description>need not permissions</description>
</property>
说明：dfs.permissions配置为false后，可以允许不要检查权限就生成dfs上的文件，方便倒是方便了，但是你需要防止误删除，请将它设置为true，或者直接将该property节点删除，因为默认就是true。
D.新建并且修改mapred-site.xml
在该版本中，有一个名为mapred-site.xml.template的文件，复制该文件，然后改名为mapred-site.xml，
<property>
<name>mapred.job.tracker</name>
<value>192.168.137.94:9001</value>
</property>
<property>
<name>mapred.local.dir</name>
<value>/root/hadoop/var</value>
</property>
<property>
<name>mapreduce.framework.name</name>
<value>yarn</value>
</property>
E.修改slaves文件
修改/opt/hadoop/hadoop-2.8.0/etc/hadoop/slaves文件，将里面的localhost删除，添加如下内容：
192.168.137.120
192.168.137.183
F. 修改yarn-site.xml文件
修改/opt/hadoop/hadoop-2.8.0/etc/hadoop/yarn-site.xml文件，
在<configuration>节点内加入配置(注意了，内存根据机器配置越大越好，我这里只配2个G是因为机器不行):
<property>
<name>yarn.resourcemanager.hostname</name>
<value>192.168.137.94</value>
</property>
<property>
<description>The address of the applications manager interface in the RM.</description>
<name>yarn.resourcemanager.address</name>
<value>${yarn.resourcemanager.hostname}:8032</value>
</property>
<property>
<description>The address of the scheduler interface.</description>
<name>yarn.resourcemanager.scheduler.address</name>
<value>${yarn.resourcemanager.hostname}:8030</value>
</property>
<property>
<description>The http address of the RM web application.</description>
<name>yarn.resourcemanager.webapp.address</name>
<value>${yarn.resourcemanager.hostname}:8088</value>
</property>
<property>
<description>The https adddress of the RM web application.</description>
<name>yarn.resourcemanager.webapp.https.address</name>
<value>${yarn.resourcemanager.hostname}:8090</value>
</property>
<property>
<name>yarn.resourcemanager.resource-tracker.address</name>
<value>${yarn.resourcemanager.hostname}:8031</value>
</property>
<property>
<description>The address of the RM admin interface.</description>
<name>yarn.resourcemanager.admin.address</name>
<value>${yarn.resourcemanager.hostname}:8033</value>
</property>
<property>
<name>yarn.nodemanager.aux-services</name>
<value>mapreduce_shuffle</value>
</property>
<property>
<name>yarn.scheduler.maximum-allocation-mb</name>
<value>2048</value>
<discription>每个节点可用内存,单位MB,默认8182MB</discription>
</property>
<property>
<name>yarn.nodemanager.vmem-pmem-ratio</name>
<value>2.1</value>
</property>
<property>
<name>yarn.nodemanager.resource.memory-mb</name>
<value>2048</value>
</property>
<property>
<name>yarn.nodemanager.vmem-check-enabled</name>
<value>false</value>
</property>
说明：yarn.nodemanager.vmem-check-enabled这个的意思是忽略虚拟内存的检查，如果你是安装在虚拟机上，这个配置很有用，配上去之后后续操作不容易出问题。如果是实体机上，并且内存够多，可以将这个配置去掉。