Hadoop初体验:快速搭建Hadoop伪分布式环境
0.前言
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本文旨在使用一个全新安装好的Linux系统从0开始进行Hadoop伪分布式环境的搭建,以达到快速搭建的目的,从而体验Hadoop的魅力所在,为后面的继续学习提供基础环境。
对使用的系统环境作如下说明:
操作系统:CentOS 6.5 64位
主机IP地址:10.0.0.131/24
主机名:leaf
用户名:root
hadoop版本:2.6.5
jdk版本:1.7
可以看到,这里直接使用root用户,而不是按照大多数的教程创建一个hadoop用户来进行操作,就是为了达到快速搭建Hadoop环境以进行体验的目的。
为了保证后面的操作能够正常完成,请先确认本机是否可以解析到主机名leaf,如果不能,请手动添加解析到/etc/hosts目录中:
[root@leaf ~]# echo "127.0.0.1 leaf" >> /etc/hosts [root@leaf ~]# ping leaf PING leaf (127.0.0.1) 56(84) bytes of data. 64 bytes from localhost (127.0.0.1): icmp_seq=1 ttl=64 time=0.043 ms 64 bytes from localhost (127.0.0.1): icmp_seq=2 ttl=64 time=0.048 ms 64 bytes from localhost (127.0.0.1): icmp_seq=3 ttl=64 time=0.046 ms
1.rsync软件安装
使用下面命令安装:
[root@leaf ~]# yum install -y rsync
2.ssh安装与免密码登陆配置
(1)ssh安装
使用下面命令安装
[root@leaf ~]# yum install -y openssh-server openssh-clients
(2)ssh免密码登陆配置
因为Hadoop使用ssh协议来管理远程守护进程,所以需要配置免密码登陆。
关闭防火墙和selinux
为了确保能够成功配置,在配置前,先把防火墙和selinux关闭:
# 关闭防火墙 [root@leaf ~]# /etc/init.d/iptables stop [root@leaf ~]# chkconfig --level 3 iptables off # 关闭selinux [root@leaf ~]# setenforce 0 [root@leaf ~]# sed -i s/SELINUX=enforcing/SELINUX=disabled/g /etc/selinux/config [root@leaf ~]# cat /etc/selinux/config | grep disabled # disabled - No SELinux policy is loaded. SELINUX=disabled
生成密钥对
[root@leaf ~]# mkdir .ssh [root@leaf ~]# ssh-keygen -t dsa -P '' -f .ssh/id_dsa Generating public/private dsa key pair. Your identification has been saved in .ssh/id_dsa. Your public key has been saved in .ssh/id_dsa.pub. The key fingerprint is: 5b:af:7c:45:f3:ff:dc:50:f5:81:4b:1e:5c:c1:86:90 root@leaf The key's randomart p_w_picpath is: +--[ DSA 1024]----+ | .o oo.| | E..oo | | =...| | o = +| | S . + oo| | o . ...| | . ... .| | . .. oo| | o. =| +-----------------+
将公钥添加到本地信任列表
[root@leaf ~]# cat .ssh/id_dsa.pub >> .ssh/authorized_keys
验证
上面三步完成后就完成了免密码登陆的配置,可以使用下面的命令进行验证:
[root@leaf ~]# ssh localhost The authenticity of host 'localhost (::1)' can't be established. RSA key fingerprint is d1:0d:ed:eb:e7:d1:2f:02:23:70:ef:11:14:4e:fa:42. Are you sure you want to continue connecting (yes/no)? yes Warning: Permanently added 'localhost' (RSA) to the list of known hosts. Last login: Wed Aug 30 04:28:01 2017 from 10.0.0.1 [root@leaf ~]#
在第一次登陆的时候需要输入yes,之后再登陆时就可以直接登陆了:
[root@leaf ~]# ssh localhost Last login: Wed Aug 30 04:44:02 2017 from localhost [root@leaf ~]#
3.jdk安装与配置
(1)jdk下载
这里使用的是jdk1.7版本,可以到下面的网站进行下载:
http://www.oracle.com/technetwork/java/javase/downloads/java-archive-downloads-javase7-521261.html
下载完成后,可以使用winscp上传到/root目录下,如下:
[root@leaf ~]# ls -lh jdk-7u80-linux-x64.tar.gz -rw-r--r--. 1 root root 147M Aug 29 12:05 jdk-7u80-linux-x64.tar.gz
(2)jdk安装
将jdk解压到/usr/local目录下,并创建软链接:
[root@leaf ~]# cp jdk-7u80-linux-x64.tar.gz /usr/local/ [root@leaf ~]# cd /usr/local/ [root@leaf local]# tar -zxf jdk-7u80-linux-x64.tar.gz [root@leaf local]# ls -ld jdk1.7.0_80/ drwxr-xr-x. 8 uucp 143 4096 Apr 11 2015 jdk1.7.0_80/ [root@leaf local]# ln -s jdk1.7.0_80/ jdk [root@leaf local]# ls -ld jdk lrwxrwxrwx. 1 root root 12 Aug 30 04:56 jdk -> jdk1.7.0_80/
(3)JAVA_HOME环境变量配置
java命令在/usr/local/jdk/bin目录下:
[root@leaf local]# cd jdk/bin/ [root@leaf bin]# ls -lh java -rwxr-xr-x. 1 uucp 143 7.6K Apr 11 2015 java
配置java环境变量:
[root@leaf bin]# echo 'export JAVA_HOME=/usr/local/jdk/bin' >> /etc/profile [root@leaf bin]# echo 'export PATH=$PATH:$JAVA_HOME' >> /etc/profile [root@leaf bin]# source /etc/profile
这样我们就可以在任何一个目录下使用java相关的命令:
[root@leaf ~]# java -version java version "1.7.0_80" Java(TM) SE Runtime Environment (build 1.7.0_80-b15) Java HotSpot(TM) 64-Bit Server VM (build 24.80-b11, mixed mode) [root@leaf ~]# javac -version javac 1.7.0_80
4.hadoop安装与配置
(1)hadoop下载
这里使用hadoop 2.6.5版本,可以到下面的网站进行下载:
http://hadoop.apache.org/releases.html
选择2.6.5的binary进入相应的页面便可以下载,然后使用winscp上传到/root目录下,如下:
[root@leaf ~]# ls -lh hadoop-2.6.5.tar.gz -rw-r--r--. 1 root root 191M Aug 29 19:09 hadoop-2.6.5.tar.gz
(2)hadoop安装
将hadoop解压到/usr/local目录下,并创建软链接:
[root@leaf ~]# cp hadoop-2.6.5.tar.gz /usr/local [root@leaf ~]# cd /usr/local [root@leaf local]# tar -zxf hadoop-2.6.5.tar.gz [root@leaf local]# ls -ld hadoop-2.6.5 drwxrwxr-x. 9 1000 1000 4096 Oct 3 2016 hadoop-2.6.5 [root@leaf local]# ln -s hadoop-2.6.5 hadoop [root@leaf local]# ls -ld hadoop lrwxrwxrwx. 1 root root 12 Aug 30 05:05 hadoop -> hadoop-2.6.5
(3)hadoop环境变量配置
hadoop相关命令在/usr/local/hadoop/bin和/usr/local/hadoop/sbin目录下,如下所示:
[root@leaf local]# cd hadoop/bin/ [root@leaf bin]# ls -lh hadoop -rwxr-xr-x. 1 1000 1000 5.4K Oct 3 2016 hadoop
配置hadoop环境变量:
[root@leaf bin]# echo 'export HADOOP_HOME=/usr/local/hadoop/bin:/usr/local/hadoop/sbin' >> /etc/profile [root@leaf bin]# echo 'export PATH=$PATH:$HADOOP_HOME' >> /etc/profile
这样我们就可以在任何一个目录下使用hadoop相关的命令:
[root@leaf ~]# hadoop Usage: hadoop [--config confdir] COMMAND where COMMAND is one of: fs run a generic filesystem user client version print the version jarrun a jar file checknative [-a|-h] check native hadoop and compression libraries availability distcp copy file or directories recursively archive -archiveName NAME -p * create a hadoop archive classpath prints the class path needed to get the credential interact with credential providers Hadoop jar and the required libraries daemonlog get/set the log level for each daemon trace view and modify Hadoop tracing settings or CLASSNAME run the class named CLASSNAME Most commands print help when invoked w/o parameters.
(4)hadoop配置
hadoop的配置文件在/usr/local/hadoop/etc/hadoop目录下:
[root@leaf ~]# cd /usr/local/hadoop/etc/hadoop/ [root@leaf hadoop]# ls capacity-scheduler.xml hadoop-policy.xml kms-log4j.properties ssl-client.xml.example configuration.xsl hdfs-site.xml kms-site.xml ssl-server.xml.example container-executor.cfg httpfs-env.sh log4j.properties yarn-env.cmd core-site.xml httpfs-log4j.properties mapred-env.cmd yarn-env.sh hadoop-env.cmd httpfs-signature.secret mapred-env.sh yarn-site.xml hadoop-env.sh httpfs-site.xml mapred-queues.xml.template hadoop-metrics2.properties kms-acls.xml mapred-site.xml.template hadoop-metrics.properties kms-env.sh slaves
配置core-site.xml
fs.default.name hdfs://localhost:9000
fs.default.name这个字段下的值用于指定NameNode(HDFS的Master)的IP地址和端口号,如下面的value值hdfs://localhost:9000,就表示HDFS NameNode的IP地址或主机为localhost,端口号为9000.
配置hdfs-site.xml
dfs.replication 1 dfs.name.dir /root/hdfs-filesystem/name dfs.data.dir /root/hdfs-filesystem/data
dfs.replication用于指定HDFS中每个Block块被复制的次数,起到数据冗余备份的作用;dfs.name.dir用于配置HDFS的NameNode的元数据,以逗号隔开,HDFS会把元数据冗余复制到这些目录下;dfs.data.dir用于配置HDFS的DataNode的数据目录,以逗号隔开,HDFS会把数据存在这些目录下。
配置mapred-site.xml
mapred.job.tracker localhost:9001
mapred.job.tracker字段用于指定MapReduce Jobtracker的IP地址及端口号,如这里IP地址或主机为localhost,9001是MapReduce Jobtracker RPC的交互端口。
配置hadoop-env.sh
export JAVA_HOME=/usr/local/jdk
5.hadoop启动与测试
(1)格式化HDFS分布式文件系统
执行如下命令:
[root@leaf ~]# hadoop namenode -format ... 17/08/30 08:41:29 INFO namenode.NNStorageRetentionManager: Going to retain 1 p_w_picpaths with txid >= 0 17/08/30 08:41:29 INFO util.ExitUtil: Exiting with status 0 17/08/30 08:41:29 INFO namenode.NameNode: SHUTDOWN_MSG: /************************************************************ SHUTDOWN_MSG: Shutting down NameNode at leaf/127.0.0.1 ************************************************************/
注意看输出显示是不是跟上面的类似,如果是,则说明操作成功。
(2)启动hadoop服务
执行如下命令:
[root@leaf ~]# start-all.sh This script is Deprecated. Instead use start-dfs.sh and start-yarn.sh 17/08/30 08:53:22 WARN util.NativeCodeLoader: Unable to load native-hadoop library for your platform... using builtin-java classes where applicable Starting namenodes on [localhost] localhost: starting namenode, logging to /usr/local/hadoop-2.6.5/logs/hadoop-root-namenode-leaf.out localhost: starting datanode, logging to /usr/local/hadoop-2.6.5/logs/hadoop-root-datanode-leaf.out Starting secondary namenodes [0.0.0.0] 0.0.0.0: starting secondarynamenode, logging to /usr/local/hadoop-2.6.5/logs/hadoop-root-secondarynamenode-leaf.out 17/08/30 08:53:48 WARN util.NativeCodeLoader: Unable to load native-hadoop library for your platform... using builtin-java classes where applicable starting yarn daemons starting resourcemanager, logging to /usr/local/hadoop-2.6.5/logs/yarn-root-resourcemanager-leaf.out localhost: starting nodemanager, logging to /usr/local/hadoop-2.6.5/logs/yarn-root-nodemanager-leaf.out
(3)hadoop服务测试
启动完成后,执行jps命令,可以看到hadoop运行的守护进程,如下:
[root@leaf ~]# jps 4167 SecondaryNameNode 4708 Jps 3907 NameNode 4394 NodeManager 4306 ResourceManager 3993 DataNode
也可以通过在浏览器中输入地址来访问相关页面,这里访问NameNode的页面,地址为http://10.0.0.131:50070,如下:
访问DataNode的页面,地址为http://10.0.0.131:50075,如下
6.参考资料
《Hadoop核心技术》
不过需要注意的是,书上版本用的是1.x,这里用的是2.x版本。
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