Hadoop 部署
1.准备环境
硬件环境：
（1）由于分布式计算需要用到很多机器，部署时用户须提供多台机器，至于提供几台，需要根据部署计划确定。标准方式的部署计划需要6台机器。
实际上，完全模式部署Hadoop时，最低需要两台机器（一个主节点，一个从节点）即可实现完全模式部署，而使用多台机器部署（一个主节点，多个从节点），会使这种完全模式体现的更加充分（硬件方面：每台机器最低要求有1GB内存，20GB硬盘空间）
（2）环境安装
1.下载VMware Workstation并且安装。
2.下载CentOS
3.新建CentOS虚拟机:打开VMware Workstation → File→ New Virtual Machine Wizard
→ Typical → Installer disc image file(iso) → 填写用户名与密码（用户名密码建议使用joe）→填入机器名 cMaster → 直至Finish。
4.根据第3步的做法分别安装CentOS系统主机名称为cMaster,cSlave0,cSlave1.
软件环境：
（1）我们使用Linux较成熟的发行版CentOS部署Hadoop，须注意的是新装系统（CentOS）的机器不可以直接部署Hadoop，须做一些基本配置。（修改机器名，添加域名映射，关闭防火墙，安装JDK）
a.修改机器名
[joe@localhost~]$su - root #切换成root用户修改机器名
[root@localhost~]#vim /etc/sysconfig/network #编辑存储机器名文件
将HOSTNAME=localhost.localdomain改为需要的机器名（cMaster/cSlave0/cSlave1）
HOSTNAME=cMaster
b.添加域名映射
查看IP地址 ：
[root@cMaster~]#ifconfig
我的IP地址为192.168.64.139 机器名为从cMaster,则域名映射为：192.168.64.139 cMaster
192.168.64.140 cSlave0
192.168.64.141 cSlave1
[root@cMaster~]#vim /etc/hosts
将上面映射加入文件“etc/hosts”中
添加IP地址的映射
192.168.64.139 cMaster
192.168.64.140 cSlave0
192.168.64.141 cSlave1
添加域名映射后，用户就可以在cMaster上直接ping另外两台机器的机器名了，如：
[root@cMaster~]# ping cSlave0 #在机器cMaster上ping机器cSlave0
c.关闭防火墙
CentOS的防火墙iptables默认情况下会阻止机器之间通信，下面为永久关闭防火墙（其命令重启后方可生效）
[root@cMaster~]#chkconfig --level 35 iptables off
#永久关闭防火墙，重启后生效
d.安装JDK
我用到的版本是： jdk1.8.0_101
需要配置的环境变量
[root@cMaster~]#vim /etc/profile
添加如下文档：（添加到文件前面）
JAVA_HOME=/home/joe/jdk1.8.0_101
PATH=$JAVA_HOME/bin:$PATH
CLASSPATH=$JAVA_HOME/jre/lib/ext:$JAVA_HOME/lib/tools.jar
export PATH JAVA_HOME CLASSPATH
验证是否正确安装：
[root@cMaster~]#Java
如果正确安装则如下图所示：
制定部署计划
cMaster作为主节点，cSlave0,cSlave1作为从节点
（5）解压Hadoop。
分别以Joe身份登录三台机器，每台执行如下命令解压Hadoop文件
[joe@cMaster~]#tar -zxvf /home/joe/Hadoop-2.7.3.tar.gz
[joe@cSlave0~]#tar -zxvf /home/joe/Hadoop-2.7.3.tar.gz
[joe@cSlave1~]#tar -zxvf /home/joe/Hadoop-2.7.3.tar.gz
（6）配置Hadoop。
首先编辑命令进入Hadoop-env.sh文件中修改配置信息
vim /home/joe/hadoop-2.7.3/etc/hadoop/hadoop-env.sh
找到：
export JAVA_HOME=${JAVA_HOME}
修改后：
export JAVA_HOME=/home/joe/jdk1.8.0_101
1.编辑文件： vim /home/joe/hadoop-2.7.3/etc/hadoop/core-site.xml 将如下内容嵌入此文件里的configuration标签中，和上一个操作相同，三台机器都需要执行此操作
<configuration>
<property><name>hadoop.tmp.dir</name><value>/home/joe/cloudData</value></property>
<property><name>fs.defaultFS</name><value>hdfs://cMaster:8020</value></property>
</configuration>
2.编辑文件： vim /home/joe/hadoop-2.7.3/etc/hadoop/yarn-site.xml 将如下内容嵌入此文件里的configuration标签中，和上一个操作相同，三台机器都需要执行此操作
<configuration>
<property><name>yarn.resourcemanager.hostname</name><value>cMaster</value></property>
<property><name>yarn.nodemanager.aux-services</name><value>mapreduce_shuffle</value></property>
</configuration>
3. 编辑文件：将文件“/home/joe/hadoop-2.7.3/etc/hadoop/mapred-site.xml.template”重命名为“/home/joe/hadoop-2.7.3/etc/hadoop/mapred-site.xml”
编辑文件 vim /home/joe/hadoop-2.7.3/etc/hadoop/yarn-site.xml 将如下内容嵌入此文件里的configuration标签中，和上一个操作相同，三台机器都需要执行此操作
<configuration>
<property><name>mapreduce.framework.name</name><value>yarn</value></property>
</configuration>
（7）启动Hadoop。
首先，在主节点cMaster 上格式化主节点命名空间
[joe@cMaster ~]$ Hadoop-2.7.3/bin/hdfs namenode -format
[joe@cMaster ~]$ hadoop-2.7.3/sbin/hadoop-daemon.sh start namenode
[joe@cMaster ~]$ hadoop-2.7.3/sbin/yarn-daemon.sh start resourcemanager
启动从服务器：
[joe@cSlave0 ~]$ hadoop-2.7.3/sbin/hadoop-daemon.sh start datanode
[joe@cSlave0 ~]$ hadoop-2.7.3/sbin/yarn-daemon.sh start nodemanager
[joe@cSlave1 ~]$ hadoop-2.7.3/sbin/hadoop-daemon.sh start datanode
[joe@cSlave1 ~]$ hadoop-2.7.3/sbin/yarn-daemon.sh start nodemanager
[joe@cSlave1 ~]$ /home/joe/jdk1.8.0_101/bin/jps
2916 NodeManager
2848 DataNode
3001 Jps
例题5.6
[joe@cMaster hadoop-2.7.3]$ bin/hdfs dfs -put /home/joe/hadoop-2.7.3/etc/hadoop/* /in
[joe@cMaster hadoop-2.7.3]$ bin/hdfs dfs -mkdir /in
mkdir: Call From cMaster/192.168.64.139 to cMaster:8020 failed on connection exception: java.net.ConnectException: Connection refused; For more details see: http://wiki.apache.org/hadoop/ConnectionRefused
[joe@cMaster hadoop-2.7.3]$ bin/hdfs dfs -put /home/joe/hadoop-2.7.3/etc/hadoop/* /in
put: Call From cMaster/192.168.64.139 to cMaster:8020 failed on connection exception: java.net.ConnectException: Connection refused; For more details see: http://wiki.apache.org/hadoop/ConnectionRefused
[joe@cMaster hadoop-2.7.3]$ bin/hadoop jar share/hadoop/mapreduce/hadoop-mapreduce-examples-2.7.3.jar wordcount /in /out/wc-01
16/10/02 14:32:54 INFO client.RMProxy: Connecting to ResourceManager at cMaster/192.168.64.139:8032
16/10/02 14:32:54 ERROR security.UserGroupInformation: PriviledgedActionException as:joe (auth:SIMPLE) cause:java.net.ConnectException: Call From cMaster/192.168.64.139 to cMaster:8020 failed on connection exception: java.net.ConnectException: Connection refused; For more details see: http://wiki.apache.org/hadoop/ConnectionRefused
java.net.ConnectException: Call From cMaster/192.168.64.139 to cMaster:8020 failed on connection exception: java.net.ConnectException: Connection refused; For more details see: http://wiki.apache.org/hadoop/ConnectionRefused
at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:57)
at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45)
at java.lang.reflect.Constructor.newInstance(Constructor.java:526)
at org.apache.hadoop.net.NetUtils.wrapWithMessage(NetUtils.java:783)
at org.apache.hadoop.net.NetUtils.wrapException(NetUtils.java:730)
at org.apache.hadoop.ipc.Client.call(Client.java:1351)
at org.apache.hadoop.ipc.Client.call(Client.java:1300)
at org.apache.hadoop.ipc.ProtobufRpcEngine$Invoker.invoke(ProtobufRpcEngine.java:206)
at com.sun.proxy.$Proxy9.getFileInfo(Unknown Source)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:606)
at org.apache.hadoop.io.retry.RetryInvocationHandler.invokeMethod(RetryInvocationHandler.java:186)
at org.apache.hadoop.io.retry.RetryInvocationHandler.invoke(RetryInvocationHandler.java:102)
at com.sun.proxy.$Proxy9.getFileInfo(Unknown Source)
at org.apache.hadoop.hdfs.protocolPB.ClientNamenodeProtocolTranslatorPB.getFileInfo(ClientNamenodeProtocolTranslatorPB.java:651)
at org.apache.hadoop.hdfs.DFSClient.getFileInfo(DFSClient.java:1679)
at org.apache.hadoop.hdfs.DistributedFileSystem$17.doCall(DistributedFileSystem.java:1106)
at org.apache.hadoop.hdfs.DistributedFileSystem$17.doCall(DistributedFileSystem.java:1102)
at org.apache.hadoop.fs.FileSystemLinkResolver.resolve(FileSystemLinkResolver.java:81)
at org.apache.hadoop.hdfs.DistributedFileSystem.getFileStatus(DistributedFileSystem.java:1102)
at org.apache.hadoop.fs.FileSystem.exists(FileSystem.java:1397)
at org.apache.hadoop.mapreduce.lib.output.FileOutputFormat.checkOutputSpecs(FileOutputFormat.java:145)
at org.apache.hadoop.mapreduce.JobSubmitter.checkSpecs(JobSubmitter.java:456)
at org.apache.hadoop.mapreduce.JobSubmitter.submitJobInternal(JobSubmitter.java:342)
at org.apache.hadoop.mapreduce.Job$10.run(Job.java:1268)
at org.apache.hadoop.mapreduce.Job$10.run(Job.java:1265)
at java.security.AccessController.doPrivileged(Native Method)
at javax.security.auth.Subject.doAs(Subject.java:415)
at org.apache.hadoop.security.UserGroupInformation.doAs(UserGroupInformation.java:1491)
at org.apache.hadoop.mapreduce.Job.submit(Job.java:1265)
at org.apache.hadoop.mapreduce.Job.waitForCompletion(Job.java:1286)
at org.apache.hadoop.examples.WordCount.main(WordCount.java:84)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:606)
at org.apache.hadoop.util.ProgramDriver$ProgramDescription.invoke(ProgramDriver.java:72)
at org.apache.hadoop.util.ProgramDriver.run(ProgramDriver.java:144)
at org.apache.hadoop.examples.ExampleDriver.main(ExampleDriver.java:74)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:606)
at org.apache.hadoop.util.RunJar.main(RunJar.java:212)
Caused by: java.net.ConnectException: Connection refused
at sun.nio.ch.SocketChannelImpl.checkConnect(Native Method)
at sun.nio.ch.SocketChannelImpl.finishConnect(SocketChannelImpl.java:735)
at org.apache.hadoop.net.SocketIOWithTimeout.connect(SocketIOWithTimeout.java:206)
at org.apache.hadoop.net.NetUtils.connect(NetUtils.java:529)
at org.apache.hadoop.net.NetUtils.connect(NetUtils.java:493)
at org.apache.hadoop.ipc.Client$Connection.setupConnection(Client.java:547)
at org.apache.hadoop.ipc.Client$Connection.setupIOstreams(Client.java:642)
at org.apache.hadoop.ipc.Client$Connection.access$2600(Client.java:314)
at org.apache.hadoop.ipc.Client.getConnection(Client.java:1399)
at org.apache.hadoop.ipc.Client.call(Client.java:1318)
... 40 more