hadoop学习笔记

hadoop集群搭建

hadoop摘要
Hadoop 是一个开源的分布式存储和计算框架，旨在处理大规模数据集并提供高可靠性、高性能的数据处理能力。它主要包括以下几个核心组件：

• Hadoop 分布式文件系统（HDFS）：HDFS 是 Hadoop 的分布式文件存储系统，用于存储大规模数据，并通过数据的副本和自动故障恢复机制来提供高可靠性和容错性。

• YARN（Yet Another Resource Negotiator）：YARN 是 Hadoop 的资源管理平台，用于调度和管理集群中的计算资源，支持多种数据处理框架的并行计算，如 MapReduce、Spark 等。

• MapReduce：MapReduce 是 Hadoop 最初提出的一种分布式计算编程模型，用于并行处理大规模数据集。它将计算任务分解为 Map 和 Reduce 两个阶段，充分利用集群的计算资源进行并行计算。

• Hadoop 生态系统：除了上述核心组件外，Hadoop 还包括了一系列相关项目和工具，如 HBase（分布式列存数据库）、Hive（数据仓库基础设施）、Spark（快速通用的集群计算系统）等，构成了完整的大数据处理生态系统。

总的来说，Hadoop 提供了一套强大的工具和框架，使得用户能够在分布式环境下高效地存储、处理和分析大规模数据，是大数据领域的重要基础设施之一。

基础环境

规划

关闭防火墙 安全模块

systemctl disable --now firewalld 
#关闭并且禁止防火墙自启动
setenforce 0
#关闭增强模块
sed -i 's/SELINUX=enforcing/SELINUX=permissive/g'  /etc/selinux/config
#禁止自启动

添加主机地址映射

cat >> /etc/hosts << lxf
192.168.200.41 hadoop001
192.168.200.42 hadoop002
192.168.200.43 hadoop003
lxf

传递软件包

#最好创建一个独立目录存放软件包
#
[root@hadoop001 ~]# mkdir -p /export/{data,servers,software}
[root@hadoop001 ~]# tree /export/
/export/
├── data     #存放数据
├── servers  #安装服务
└── software #存放服务的软件包3 directories, 0 files
[root@hadoop001 ~]# 

配置ssh免密

master 和两台slave都要配置免密

#在hadoop001节点
[root@hadoop001 ~]#
[root@hadoop001 ~]# ssh-keygen -t rsa 
[root@hadoop001 ~]#
Generating public/private rsa key pair.
Enter file in which to save the key (/root/.ssh/id_rsa): 
Enter passphrase (empty for no passphrase): 
Enter same passphrase again: 
Your identification has been saved in /root/.ssh/id_rsa.
Your public key has been saved in /root/.ssh/id_rsa.pub.
The key fingerprint is:
SHA256:2AY6p3kFWziXFmXH7e/PHgrAVZ9H7hkCWAtCc19UwZw root@hadoop001
The key's randomart image is:
+---[RSA 2048]----+
|      .+.+=+o=+o+|
|       .+=o.* oE.|
|      = =  + o +o|
|     . @. .   o.+|
|    o + So     o.|
|     = o  .     .|
|    o .    .   o |
|     .      . ..o|
|             . .=|
+----[SHA256]-----+
[root@hadoop001 ~]#
[root@hadoop001 ~]# hosts=("hadoop001" "hadoop002" "hadoop003"); for host in "${hosts[@]}"; do echo "将公钥分发到 $host"; ssh-copy-id  $host; done
将公钥分发到 hadoop001
/usr/bin/ssh-copy-id: INFO: Source of key(s) to be installed: "/root/.ssh/id_rsa.pub"
/usr/bin/ssh-copy-id: INFO: attempting to log in with the new key(s), to filter out any that are already installed
/usr/bin/ssh-copy-id: INFO: 1 key(s) remain to be installed -- if you are prompted now it is to install the new keys
root@hadoop001's password: Number of key(s) added: 1Now try logging into the machine, with:   "ssh 'hadoop001'"
and check to make sure that only the key(s) you wanted were added.将公钥分发到 hadoop002
/usr/bin/ssh-copy-id: INFO: Source of key(s) to be installed: "/root/.ssh/id_rsa.pub"
The authenticity of host 'hadoop002 (192.168.200.42)' can't be established.
ECDSA key fingerprint is SHA256:ADFjDGD2MxgCqL5fQuWhn+0T5drPiTXERvlMiu/QXjA.
ECDSA key fingerprint is MD5:d2:2b:06:cb:13:48:e0:87:d7:f3:87:8b:2c:56:e4:da.
Are you sure you want to continue connecting (yes/no)? yes
/usr/bin/ssh-copy-id: INFO: attempting to log in with the new key(s), to filter out any that are already installed
/usr/bin/ssh-copy-id: INFO: 1 key(s) remain to be installed -- if you are prompted now it is to install the new keys
root@hadoop002's password: Number of key(s) added: 1Now try logging into the machine, with:   "ssh 'hadoop002'"
and check to make sure that only the key(s) you wanted were added.将公钥分发到 hadoop003
/usr/bin/ssh-copy-id: INFO: Source of key(s) to be installed: "/root/.ssh/id_rsa.pub"
/usr/bin/ssh-copy-id: INFO: attempting to log in with the new key(s), to filter out any that are already installed
/usr/bin/ssh-copy-id: INFO: 1 key(s) remain to be installed -- if you are prompted now it is to install the new keys
root@hadoop003's password: Number of key(s) added: 1Now try logging into the machine, with:   "ssh 'hadoop003'"
and check to make sure that only the key(s) you wanted were added.
[root@hadoop001 ~]#
[root@hadoop001 ~]# 
#在hadoop002和hadoop003重复操作 使得三台节点可以互相通信

安装服务

安装java hadoop

[root@hadoop001]# tree -L 2 /export/
/export/
├── data      #因为还没有启动服务所以没有数据文件
├── servers
│   ├── hadoop-3.3.6
│   └── jdk1.8.0_221
└── software├── hadoop-3.3.6-aarch64.tar.gz└── jdk-8u221-linux-x64.tar.gz5 directories, 2 files
[root@hadoop001 export]# 
#同样在另外两个节点分别解压到对应目录

配置环境变量

#/etc/profile.d/my_env.sh  我们可以专门为hadoop设置一个环境变量文件夹用作修改，而不去直接修改/etc/profile文件，这样在系统启动时或者用户登录时会自动加载这些环境变量。[root@hadoop001 ~]# cat >> /etc/profile.d/my_env.sh << lxf 
> #JAVA_HOME
> export JAVA_HOME=/export/servers/jdk1.8.0_221
> export PATH=$PATH:$JAVA_HOME/bin
> #HADOOP_HOME
> export HADOOP_HOME=/export/servers/hadoop-3.3.6
> export PATH=$PATH:$HADOOP_HOME/bin
> export PATH=$PATH:$HADOOP_HOME/sbin
> lxf
[root@hadoop001 ~]# source /etc/profile
[root@hadoop001 ~]# echo $HADOOP_HOME
/export/servers/hadoop-3.3.6
[root@hadoop001 ~]# echo $JAVA_HOME
/export/servers/jdk1.8.0_221
[root@hadoop001 ~]# #测试环境变量
[root@hadoop001 ~]# hadoop version 
Hadoop 3.3.6
Source code repository https://github.com/apache/hadoop.git -r 1be78238728da9266a4f88195058f08fd012bf9c
Compiled by ubuntu on 2023-06-18T23:15Z
Compiled on platform linux-aarch_64
Compiled with protoc 3.7.1
From source with checksum 5652179ad55f76cb287d9c633bb53bbd
This command was run using /export/servers/hadoop-3.3.6/share/hadoop/common/hadoop-common-3.3.6.jar
[root@hadoop001 ~]# java -version 
java version "1.8.0_221"
Java(TM) SE Runtime Environment (build 1.8.0_221-b11)
Java HotSpot(TM) 64-Bit Server VM (build 25.221-b11, mixed mode)
[root@hadoop001 ~]# 
#分发环境配置文件
scp /etc/profile.d/my_env.sh hadoop002:/etc/profile.d/my_env.sh
scp /etc/profile.d/my_env.sh hadoop003:/etc/profile.d/my_env.sh
#分发完成后注意测试环境变量是否成功配置

修改Hadoop配置文件

[root@hadoop001 hadoop]# pwd
/export/servers/hadoop-3.3.6/etc/hadoop
[root@hadoop001 hadoop]# grep  '^export' hadoop-env.sh
export  JAVA_HOME=/export/servers/jdk1.8.0_221
export HDFS_NAMENODE_USER="root"
export HDFS_DATANODE_USER="root"
export HDFS_SECONDARYNAMENODE_USER="root"
export YARN_RESOURCEMANAGER_USER="root"
export YARN_NODEMANAGER_USER="root"
export HADOOP_OS_TYPE=${HADOOP_OS_TYPE:-$(uname -s)}
[root@hadoop001 hadoop]# 

修改core-site.xml文件

<configuration><property><name>fs.defaultFS</name><value>hdfs://hadoop001:9000</value></property><property><name>hadoop.tmp.dir</name><value>/export/data/hadoop/tmp</value></property>
</configuration>

修改hdfs-site.xml文件

<configuration><property><name>dfs.relication</name><value>2</value></property><property><name>dfs.namenode.name.dir</name><value>/export/data/hadoop/name</value></property><property><name>dfs.namenode.secondary.http-address</name><value>hadoop002:50090</value></property><property><name>dfs.namenode.data.dir</name><value>/export/data/hadoop/data</value></property>
</configuration>

修改mapred-site.xml文件

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

修改yarn-site.xml文件

<configuration>
<!-- Site specific YARN configuration properties --><property><name>yarn.nodemanager.aux-services</name><value>mapreduce_shuffle</value></property><property><name>yarn.resourcemanager.hostname</name><value>hadoop001</value></property>
</configuration>

修改workers文件

[root@hadoop001 hadoop]# cat >>  workers  << lxf 
> hadoop001
> hadoop002
> hadoop003
> lxf
[root@hadoop001 hadoop]# 

向集群分发配置文件

#开始分发
#向hadoop002
scp /export/servers/hadoop-3.3.6/etc/hadoop hadoop002:/export/servers/hadoop-3.3.6/etc/hadoop
#向hadoop003
scp /export/servers/hadoop-3.3.6/etc/hadoop hadoop002:/export/servers/hadoop-3.3.6/etc/hadoop

hadoop集群

hadoop集群文件系统初始化

Hadoop集群的初始化是非常重要的，它确保了集群的各个组件在启动时处于正确的状态，并且能够正确地协调彼此的工作。在第一次启动Hadoop集群时，初始化是必需的，具体原因如下：

• 文件系统初始化：Hadoop的分布式文件系统（HDFS）需要在启动时进行初始化，这包括创建初始的目录结构、设置权限和准备必要的元数据等操作。
• 元数据准备：Hadoop的各个组件（比如NameNode、ResourceManager等）需要进行元数据的准备工作，包括创建必要的数据库表、清理日志文件等。
• 配置检查：初始化过程还会对各个节点的配置进行检查，确保配置的正确性和一致性，以避免在后续运行中出现问题。
• 启动必要的服务：在初始化过程中，Hadoop会启动各个必要的服务，比如NameNode、DataNode、ResourceManager、NodeManager等，以确保集群的核心组件都能够正常运行。

#在启动hadoop集群之前，需要对主节点hadoop001进行格式化
[root@hadoop001 ~]# hadoop namenode -format
.......
......

启动

分布启动

启动hdfs

[root@hadoop001 ~]# start-dfs.sh 

启动yarn

[root@hadoop001 ~]# start-yarn.sh 

集群一键启动

[root@hadoop001 ~]# start-all.sh 

关闭

分布关闭

关闭hdfs

[root@hadoop001 ~]# stop-dfs.sh 

启动yarn

[root@hadoop001 ~]# stop-yarn.sh 

集群一键启动

[root@hadoop001 ~]# stop-all.sh 

测试

查看hadoop的WebUI

成功访问

可以在C:\Windows\System32\drivers\etc\hosts下面修改hosts主机地址映射然后在宿主机的浏览器中就可以使用主机名:端口号去访问

如果没有设置就只能使用ip:端口号去访问

关闭hdfs

[root@hadoop001 ~]# stop-dfs.sh 

启动yarn

[root@hadoop001 ~]# stop-yarn.sh 

集群一键启动

[root@hadoop001 ~]# stop-all.sh 

测试

查看hadoop的WebUI

成功访问

可以在C:\Windows\System32\drivers\etc\hosts下面修改hosts主机地址映射然后在宿主机的浏览器中就可以使用主机名:端口号去访问

如果没有设置就只能使用ip:端口号去访问