Hadoop学习(5)-----hadoop 2.6的安装

1 介绍

为了解决Hadoop 1.x框架中的问题：例如单namenode节点问题等问题，Apache基金会推出新一代的hadoop框架，Hadoop 2.x系列版本，在该版本中，HDFS的一些机制进行了改善，并且Hadoop的MapReduce框架升级为YARY框架（MapReduce 2），并且实现了与spark等现在叫流行的大数据分析框架的集成。关于Hadoop 2.x系列，我们将会在后面详细讲解到

2 安装hadoop 2.6

因为hadoop的安装所需要的环境是相同的，和hadoop 1.2.1版本的安装环境是相同的，在这里笔者将安装前的准备工作进行了简化

（1）安装sshd服务，并且实现节点之间的免密码登录。

因为在hadoop 2.x中，将JobTrack的任务调度和资源管理两个任务进行了分离，分别分布在不同的节点上，所以需要在安装namenode服务的节点上和安装ResourceManager服务的节点上都实现和所有节点实现免密码登录。

（2）配置hosts文件

本集群只实现了四个节点，节点名称与IP地址如下：

192.168.149.129	hadoop1
192.168.149.130	hadoop2
192.168.149.131	hadoop3
192.168.149.132	hadoop4

（3）安装Java1.7

安装Java1.7 已经在hadoop1.2.1安装过程中详细解释了。这里只是简单显示了Java的一些配置

[hadoop@hadoop1 etc]$ ls /opt/
apache-ant-1.9.5  apache-maven-3.3.3  jdk1.7.0_75  protobuf  protobuf-2.5.0  rh
[hadoop@hadoop1 etc]$ cat /etc/profile
# /etc/profile

# System wide environment and startup programs, for login setup
# Functions and aliases go in /etc/bashrc

# It's NOT a good idea to change this file unless you know what you
# are doing. It's much better to create a custom.sh shell script in
# /etc/profile.d/ to make custom changes to your environment, as this
# will prevent the need for merging in future updates.

pathmunge () {
case ":${PATH}:" in
*:"$1":*)
;;
*)
if [ "$2" = "after" ] ; then
PATH=$PATH:$1
else
PATH=$1:$PATH
fi
esac
}

if [ -x /usr/bin/id ]; then
if [ -z "$EUID" ]; then
# ksh workaround
EUID=`id -u`
UID=`id -ru`
fi
USER="`id -un`"
LOGNAME=$USER
MAIL="/var/spool/mail/$USER"
fi

# Path manipulation
if [ "$EUID" = "0" ]; then
pathmunge /sbin
pathmunge /usr/sbin
pathmunge /usr/local/sbin
else
pathmunge /usr/local/sbin after
pathmunge /usr/sbin after
pathmunge /sbin after
fi

HOSTNAME=`/bin/hostname 2>/dev/null`
HISTSIZE=1000
if [ "$HISTCONTROL" = "ignorespace" ] ; then
export HISTCONTROL=ignoreboth
else
export HISTCONTROL=ignoredups
fi

export PATH USER LOGNAME MAIL HOSTNAME HISTSIZE HISTCONTROL

# By default, we want umask to get set. This sets it for login shell
# Current threshold for system reserved uid/gids is 200
# You could check uidgid reservation validity in
# /usr/share/doc/setup-*/uidgid file
if [ $UID -gt 199 ] && [ "`id -gn`" = "`id -un`" ]; then
umask 002
else
umask 022
fi

for i in /etc/profile.d/*.sh ; do
if [ -r "$i" ]; then
if [ "${-#*i}" != "$-" ]; then
. "$i"
else
. "$i" >/dev/null 2>&1
fi
fi
done

#Java Install
export JAVA_HOME=/opt/jdk1.7.0_75
export CLASSPATH=/opt/jdk1.7.0_75/lib/tools.jar:.:/opt/jdk1.7.0_75/lib/dt.jar
export PATH=$PATH:/opt/jdk1.7.0_75/jre/bin:/opt/jdk1.7.0_75/bin
#hadoop-2.6.0 install
export HADOOP_HOME=/home/hadoop/hadoop-2.6.0
export PATH=$PATH:/home/hadoop/hadoop-2.6.0/bin:/home/hadoop/hadoop-2.6.0/sbin

#maven install
export MAVEN_HOME=/opt/apache-maven-3.3.3
export PATH=$PATH:/opt/apache-maven-3.3.3/bin

#ant install
export ANT_HOME=/opt/apache-ant-1.9.5
export PATH=$PATH:/opt/apache-ant-1.9.5/bin

#protobuf install
export PATH=$PATH:/opt/protobuf/bin

unset i
unset -f pathmunge

（4）安装Hadoop 2.6

1）Hadoop 2.6下载

Hadoop 2.6的下载地址为：http://www.apache.org/dyn/closer.cgi/hadoop/common；从该页面中选取下载地址，从中下载相应的Hadoop 2.6的版本

2）在hadoop用户下进行解压，并放在hadoop的家目录下

[hadoop@hadoop1 sources]$ ls
apache-ant-1.9.5-bin.tar.gz    hadoop-2.6.0-src.tar.gz    protobuf-2.5.0.tar.gz
apache-maven-3.3.3-bin.tar.gz  hadoop-2.6.0.tar.gz
hadoop-2.6.0-src               jdk-7u75-linux-x64.tar.gz
[hadoop@hadoop1 sources]$ tar -zxf hadoop-2.6.0.tar.gz
[hadoop@hadoop1 sources]$ ls
apache-ant-1.9.5-bin.tar.gz    hadoop-2.6.0-src         jdk-7u75-linux-x64.tar.gz
apache-maven-3.3.3-bin.tar.gz  hadoop-2.6.0-src.tar.gz  protobuf-2.5.0.tar.gz
hadoop-2.6.0                   hadoop-2.6.0.tar.gz
[hadoop@hadoop1 sources]$ pwd
/home/hadoop/sources
[hadoop@hadoop1 sources]$ mv hadoop-2.6.0 ../

3）配置Hadoop 2.6的环境变量

hadoop的环境变量配置是hadoop安装的核心，所有的配置文件全部放在/home/hadoop/hadoop-2.6.0/etc/hadoop目录下

（A）对hadoop-env.sh和yarn-env.sh文件进行Java环境变量的配置

hadoop-env.sh

# The java implementation to use.
export JAVA_HOME=/opt/jdk1.7.0_75

yarn-env.sh

# some Java parameters
export JAVA_HOME=/opt/jdk1.7.0_75

（B）core-site.xml

<property>
<name>fs.defaultFS</name>
<value>hdfs://192.168.149.129:9000</value>
</property>
<property>
<name>io.file.buffer.size</name>
<value>4096</value>
</property>

fs.defaultFS属性：和hadoop1.2.1中的fs.default.name属性相同，制定hdfs的入口位置。

io.file.buffer.size属性：在文件读取过程中的缓存，该属性配置的越大，文件的读取速度越快，但是相应的所需要的内存就会增加。设置一般为文件系统页面的大小（4K）的倍数

core-site.xml文件配置内容详细参考：http://hadoop.apache.org/docs/r2.6.0/hadoop-project-dist/hadoop-common/core-default.xml

（C）hdfs-site.xml

<configuration>
<property>
<name>dfs.namenode.name.dir</name>
<value>file:///home/hadoop/hadoop-2.6.0/data/hdfs/namenode</value>
</property>
<property>
<name>dfs.namenode.secondary.http-address</name>
<value>192.168.149.129:50090</value>
</property>
<property>
<name>dfs.datanode.data.dir</name>
<value>file:///home/hadoop/hadoop-2.6.0/data/hdfs/datanode</value>
</property>
<property>
<name>dfs.replication</name>
<value>1</value>
</property>
</configuration>

dfs.namenode.name.dir属性：该属性表示hadoop集群中namenode节点上的文件元数据、系统文件树镜像和edits文件存放的位置。

dir.namenode.secondary.http-address属性：表示secondary节点的访问入口。

dfs.datanode.data.dir属性：表示在datanode节点中数据块（Block）所存放的位置

dfs.replication属性：hadoop集群中文件冗余的份数

hdfs-site.xml配置详细参考：http://hadoop.apache.org/docs/r2.6.0/hadoop-project-dist/hadoop-hdfs/hdfs-default.xml

（C）mapred-site.xml

<configuration>
<property>
<name>mapreduce.framework.name</name>
<value>yarn</value>
</property>
</configuration>

mapreduce.framework.name属性：表示Mapreduce处理方案使用的YARN框架，默认情况下为local

mapred-site.xml配置详细参考：http://hadoop.apache.org/docs/r2.6.0/hadoop-mapreduce-client/hadoop-mapreduce-client-core/mapred-default.xml

（D）yarn-site.xml

<configuration>

<!-- Site specific YARN configuration properties -->
<property>
<name>yarn.nodemanager.aux-services</name>
<value>mapreduce_shuffle</value>
</property>
</configuration>

yarn.nodemanager.aux-services属性：本来该属性的默认值为mapreduce.shuffle，如果从hadoop 2.2以后这样的写法将无法启动集群，只有改成mapreduce_shuffle集群才能正常的启动。

yarn-site.xml配置详细参考：http://hadoop.apache.org/docs/r2.6.0/hadoop-yarn/hadoop-yarn-common/yarn-default.xml

（5）slaves

[hadoop@hadoop1 hadoop]$ cat slaves
192.168.149.131
192.168.149.132

该文件是datanode节点的IP地址。

当配置完配置环境中，然后将hadoop-2.6.0文件传到每一个节点中

scp -r hadoop-2.6.0/ hadoop@hadoop2:/home/hadoop/

（5）格式化hadoop集群

在格式化之前，要求需要将四个节点上的所有防火墙和selinux全部关闭，默认情况下都是关闭的，如果以防万一可以切换到root用户下，通过 chkconfig iptables off 命令关闭节点上的防火墙。然后进入到任何一个节点中的hadoop-2.6.0文件夹，执行下面的命令：

./bin/hadoop namenode -format

（6）启动hadoop2.6集群

为了更好的使用hadoop集群，可以讲hadoop的命令加载到环境变量PATH中：

[hadoop@hadoop1 ~]$ vim /etc/profile
#hadoop-2.6.0 install
export HADOOP_HOME=/home/hadoop/hadoop-2.6.0
export PATH=$PATH:/home/hadoop/hadoop-2.6.0/bin:/home/hadoop/hadoop-2.6.0/sbin

然后就是启动我们的 hadoop集群了：

首先我们要进入到ResourceManager节点中，启动资源管理程序：

[hadoop@hadoop2 ~]$ start-yarn.sh
starting yarn daemons
starting resourcemanager, logging to /home/hadoop/hadoop-2.6.0/logs/yarn-hadoop-resourcemanager-hadoop2.out
192.168.149.132: starting nodemanager, logging to /home/hadoop/hadoop-2.6.0/logs/yarn-hadoop-nodemanager-hadoop4.out
192.168.149.131: starting nodemanager, logging to /home/hadoop/hadoop-2.6.0/logs/yarn-hadoop-nodemanager-hadoop3.out
[hadoop@hadoop2 ~]$ jps
27413 Jps

然后进入namenode节点，启动所有的进程：

[hadoop@hadoop1 ~]$ start-all.sh
This script is Deprecated. Instead use start-dfs.sh and start-yarn.sh
15/06/17 08:30:30 WARN util.NativeCodeLoader: Unable to load native-hadoop library for your platform... using builtin-java classes where applicable
Starting namenodes on [hadoop1]
hadoop1: starting namenode, logging to /home/hadoop/hadoop-2.6.0/logs/hadoop-hadoop-namenode-hadoop1.out
192.168.149.132: starting datanode, logging to /home/hadoop/hadoop-2.6.0/logs/hadoop-hadoop-datanode-hadoop4.out
192.168.149.131: starting datanode, logging to /home/hadoop/hadoop-2.6.0/logs/hadoop-hadoop-datanode-hadoop3.out
Starting secondary namenodes [hadoop1]
hadoop1: starting secondarynamenode, logging to /home/hadoop/hadoop-2.6.0/logs/hadoop-hadoop-secondarynamenode-hadoop1.out
15/06/17 08:31:02 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 /home/hadoop/hadoop-2.6.0/logs/yarn-hadoop-resourcemanager-hadoop1.out
192.168.149.132: nodemanager running as process 24754. Stop it first.
192.168.149.131: nodemanager running as process 27169. Stop it first.
[hadoop@hadoop1 ~]$ jps
8922 NameNode
9242 ResourceManager
9498 Jps
9080 SecondaryNameNode

datanode节点的信息：

[hadoop@hadoop3 ~]$ jps
27460 Jps
27169 NodeManager
27329 DataNode
[hadoop@hadoop3 ~]$

（6）总结

hadoop2.x系列针对hadoop1.x系列的缺点做出了很大的改进，在HDFS和MapReduce框架中都做出了很大的改变，并且实现了和现主流大数据框架spark等的集合。

（7）修正

在hadoop2.x系列中，要求ResourceManager进程单独分布在一个节点上，所以在start-yarn.sh后，在namenode节点启动命令不是start-all.sh,因为start-all.sh会在namenode节点上也启动一个ResourceManager进程，这里应该使用的是start-dfs.sh，这样启动namenode节点和datanode节点，并且不会再namenode节点中启动ResourceManager进程。

参考文章：http://www.bkjia.com/yjs/931164.html