[大数据]CentOS7下安装Hadoop伪分布式

前提条件

拥有CentOS7服务器版环境

软件版本说明

jdk1.8

hadoop2.7.3

虚拟机环境准备

通网络

能ping通外网，例如：

ping baidu.com

如果ping不通，可以修改如下文件：

vi /etc/sysconfig/network-scripts/ifcfg-ens33

将ONBOOT=no改为ONBOOT=yes

重启网络或重启机器

重启网络

systemctl restart network

重启机器

reboot

修改主机名

将主机名从localhost改为node1，操作过程如下：

[root@localhost ~]# hostname
localhost.localdomain
[root@localhost ~]# hostnamectl set-hostname node1
[root@localhost ~]# hostname
node1
?
未重启时主机名未变
[root@localhost ~]# reboot
...
Connecting to 192.168.193.140:22...
Connection established.
To escape to local shell, press 'Ctrl+Alt+]'.
?
WARNING! The remote SSH server rejected X11 forwarding request.
Last login: Tue Mar  8 00:55:08 2022 from 192.168.193.1
[root@node1 ~]# 
重启后，命令行中的主机名改变了

新增普通用户 ?

因为root用户权限太高，误操作可能造成一些麻烦，一般情况下，我们不会用root来安装hadoop，所以我们需要创建普通用户来安装hadoop。创建新用户方法如下：

创建新用户，例如用户名为：hadoop，并设置新用户密码，重复设置2次，看不到输入的密码，这是linux的安全机制，输入即可。

[root@node1 ~]# adduser hadoop
[root@node1 ~]# passwd hadoop
Changing password for user hadoop.
New password: 
BAD PASSWORD: The password is shorter than 8 characters
Retype new password: 
passwd: all authentication tokens updated successfully.
?

给普通用户添加sudo执行权限

[root@node1 ~]# chmod -v u+w /etc/sudoers
mode of ‘/etc/sudoers’ changed from 0440 (r--r-----) to 0640 (rw-r-----)
?
[root@node1 ~]# sudo vim /etc/sudoers
在%wheel  ALL=(ALL) ? ? ? ALL一行下面添加如下语句：
hadoop ?  ALL=(ALL) ? ? ? ALL
?
[root@node1 ~]# chmod -v u-w /etc/sudoers
mode of ‘/etc/sudoers’ changed from 0640 (rw-r-----) to 0440 (r--r-----)
?

静态IP（非不要）

因为电脑连接网络不通，CentOS的IP可能会变化，可以设置静态IP来解决。

网关查询：

Vmware-->编辑-->虚拟机网络编辑器

?

注意：这里查询到网关为192.168.193.2，以自己实际查到的网关为准。

设置静态ip

[root@node1 ~]# vi /etc/sysconfig/network-scripts/ifcfg-ens33
?

修改或添加如下几项：

BOOTPROTO=static
IPADDR=192.168.193.140
GATEWAY=192.168.193.2
DNS1=192.168.193.2

注意：

1.GATEWAY和DNS1的值都填写上一步在vmware中实际查到的网关地址。

2.IPADDR为设置的静态IP地址，要与查到的网关处于同一网络，查到的网关所处的网段为192.168.193，IP地址不要与网关一致，最后一位建议设置为128-255之间，这里IP最后一位设置为140。

关闭防火墙

查看防火墙状态

[root@node1 ~]# systemctl status firewalld
● firewalld.service - firewalld - dynamic firewall daemon
 ? Loaded: loaded (/usr/lib/systemd/system/firewalld.service; disabled; vendor preset: enabled)
 ? Active: inactive (dead)
 ? ? Docs: man:firewalld(1)
[root@node1 ~]# 
?

inactive (dead)为关闭状态

如果是active (running)，为开启状态，可以用如下命令关闭防火墙

[root@node1 ~]# systemctl stop firewalld

安装hadoop伪分布式

登录普通用户

使用普通用户登录CentOS7，这里登录的普通用户为hadoop

[hadoop@node1 ~]$ 

映射IP

[hadoop@node1 ~]$ sudo vim /etc/hosts

文件末尾，添加如下内容：

192.168.193.140 node1

目录准备

创建2个目录：installfile和soft，installfile存放软件安装包，soft是软件的安装目录。

[hadoop@node1 ~]$ mkdir installfile
[hadoop@node1 ~]$ mkdir soft
[hadoop@node1 soft]$ ls
soft   installfile

安装配置jdk

官网下载jdk安装包：jdk-8u271-linux-x64.tar.gz，并将安装包上传到Linux的installfile目录。

进入安装包所在目录

cd ~/installfile

解压安装包

[hadoop@node1 installfile]$ tar -zxvf jdk-8u271-linux-x64.tar.gz -C ~/soft/

创建软链接

切换到解压目录
[hadoop@node1 installfile]$ cd ~/soft/
[hadoop@node1 soft]$ ls
jdk1.8.0_271

创建软链接
[hadoop@node1 soft]$ ln -s jdk1.8.0_271 jdk

查看软链接
[hadoop@node1 soft]$ ls
jdk  jdk1.8.0_271
?

安装nano命令（非必要，因为个人习惯使用nano编辑命令）

yum install nano -y

nano命令的功能和vi命令一样（如果不习惯用nano，后面可以用vi代替nano）。

nano的使用方法：nano 文件名，输入相关内容，保存按Ctrl+O，回车确认文件名，退出按Ctrl+X

配置环境变量

这里在.bashrc文件配置环境变量，也可以配置在/etc/profile文件。

[hadoop@node1 soft]$ nano ~/.bashrc 

在文件末尾添加如下语句

export JAVA_HOME=~/soft/jdk
export JRE_HOME=${JAVA_HOME}/jre
export CLASSPATH=.:${JAVA_HOME}/lib:${JRE_HOME}/lib 
export PATH=${JAVA_HOME}/bin:$PATH

让配置立即生效

[hadoop@node1 soft]$ source ~/.bashrc 

验证

[hadoop@node1 soft]$ java -version
java version "1.8.0_271"
Java(TM) SE Runtime Environment (build 1.8.0_271-b09)
Java HotSpot(TM) 64-Bit Server VM (build 25.271-b09, mixed mode)

能看到输出版本号即为安装配置成功。

安装配置hadoop

下载并上传安装包到Linux目录中，例如：~/installfile

[hadoop@node1 installfile]$ cd ../installfile/

解压

[hadoop@node1 installfile]$ tar -zxvf hadoop-2.7.3.tar.gz -C ~/soft/

创建软链接

[hadoop@node1 installfile]$ cd ~/soft/
[hadoop@node1 soft]$ ls
hadoop-2.7.3  jdk  jdk1.8.0_271
创建软链接
[hadoop@node1 soft]$ ln -s hadoop-2.7.3 hadoop
[hadoop@node1 soft]$ ls
hadoop  hadoop-2.7.3  jdk  jdk1.8.0_271
?

配置环境变量

nano ~/.bashrc

文件末尾添加如下内容：

export HADOOP_HOME=~/soft/hadoop
export PATH=$PATH:$HADOOP_HOME/bin:$HADOOP_HOME/sbin

让环境变量立即生效

source ~/.bashrc

验证

[hadoop@node1 soft]$ hadoop version
Hadoop 2.7.3
Subversion https://git-wip-us.apache.org/repos/asf/hadoop.git -r baa91f7c6bc9cb92be5982de4719c1c8af91ccff
Compiled by root on 2016-08-18T01:41Z
Compiled with protoc 2.5.0
From source with checksum 2e4ce5f957ea4db193bce3734ff29ff4
This command was run using /home/hadoop/soft/hadoop-2.7.3/share/hadoop/common/hadoop-common-2.7.3.jar

能看到hadoop版本号，说明环境变量设置成功。

设置免密登录，执行ssh-keygen -t rsa命令后，再连续敲击3次回车

[hadoop@node1 soft]$ ssh-keygen -t rsa
Generating public/private rsa key pair.
Enter file in which to save the key (/home/hadoop/.ssh/id_rsa): 
Created directory '/home/hadoop/.ssh'.
Enter passphrase (empty for no passphrase): 
Enter same passphrase again: 
Your identification has been saved in /home/hadoop/.ssh/id_rsa.
Your public key has been saved in /home/hadoop/.ssh/id_rsa.pub.
The key fingerprint is:
SHA256:sXZw/coSYm19gGSLdOLQGeskm+vPVr6lXENvmmQ8eeo hadoop@node1
The key's randomart image is:
+---[RSA 2048]----+
| ? ?  ..+o+ ? ?  |
| ? ? ? +oB + ? ? |
| ? ?  . B + o ?  |
| ? ? ? * * . o ? |
| ? ?  o S = o o  |
| ? ? ? + +.= = ? |
| ? ?  .  o. % +  |
| ? ? . ....B O ? |
| ? ?  .oo +oE ?  |
+----[SHA256]-----+
?

查看生成的密钥对

[hadoop@node1 soft]$ ls ~/.ssh/
id_rsa  id_rsa.pub

追加公钥，执行命令后，根据提示输入yes再次回车

[hadoop@node1 soft]$ ssh-copy-id node1
/usr/bin/ssh-copy-id: INFO: Source of key(s) to be installed: "/home/hadoop/.ssh/id_rsa.pub"
The authenticity of host 'node1 (192.168.193.140)' can't be established.
ECDSA key fingerprint is SHA256:r4LfTp6UJiZJbbxCrCaF8ouB1XEySe9c1/5d+7a39+E.
ECDSA key fingerprint is MD5:08:e4:65:b1:9a:16:5d:fd:f8:ac:13:fc:4c:88:f4:8e.
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
hadoop@node1's password: 
?
Number of key(s) added: 1
?
Now try logging into the machine, with: ? "ssh 'node1'"
and check to make sure that only the key(s) you wanted were added.
?
[hadoop@node1 soft]$ 

查看生成的认证文件authorized_keys

[hadoop@node1 soft]$ ls ~/.ssh/
authorized_keys  id_rsa  id_rsa.pub  known_hosts
?
查看认证文件内容authorized_keys
[hadoop@node1 soft]$ cat ~/.ssh/authorized_keys 
ssh-rsa AAAAB3NzaC1yc2EAAAADAQABAAABAQCuG6EHCrL93O355sr7dkLO8S75QqizvCXNQztwY0F2mrVmUZNk9BleNRE1jAirOQccFTR11SCGIhwa1klPYvGwAtY66YG+y47tsKkLc9VHoIvfpwjG3MzSwuAJhhsnv2UOIGX8kkP0/cSVT1YyfM3cJO0OzN9gB4vTE/0VUJRgGk43qO3v84kWIPTZrJlzr8wz5GSD3quteRea6Gxv7EPksWfP18sZDsynvYZ8zvXzmiv1Qf1g5Pcc52RhF0ghsZoVHB03KAPX72d4N33budSy7jnRTz81NSqnTZ8ajLOSIQVxeFk6tJwHOLW/uDQGy124PaYkiElrVyHesxJbC0Vl hadoop@node1
?
查看公钥
[hadoop@node1 soft]$ cat ~/.ssh/id_rsa.pub 
ssh-rsa AAAAB3NzaC1yc2EAAAADAQABAAABAQCuG6EHCrL93O355sr7dkLO8S75QqizvCXNQztwY0F2mrVmUZNk9BleNRE1jAirOQccFTR11SCGIhwa1klPYvGwAtY66YG+y47tsKkLc9VHoIvfpwjG3MzSwuAJhhsnv2UOIGX8kkP0/cSVT1YyfM3cJO0OzN9gB4vTE/0VUJRgGk43qO3v84kWIPTZrJlzr8wz5GSD3quteRea6Gxv7EPksWfP18sZDsynvYZ8zvXzmiv1Qf1g5Pcc52RhF0ghsZoVHB03KAPX72d4N33budSy7jnRTz81NSqnTZ8ajLOSIQVxeFk6tJwHOLW/uDQGy124PaYkiElrVyHesxJbC0Vl hadoop@node1
?
可发现，认证文件的内容和公钥一致。

验证免密登录

ssh登录到node1,不需要输入密码，注意路径的变化：由soft目录切换到了~目录，执行exit退出ssh登录
[hadoop@node1 soft]$ ssh node1
Last login: Tue Mar  8 05:54:02 2022 from 192.168.193.1
[hadoop@node1 ~]$ exit
logout
Connection to node1 closed.
[hadoop@node1 soft]$ 
?
也可以ssh ip
[hadoop@node1 soft]$ ssh 192.168.193.140
Last login: Tue Mar  8 06:16:58 2022 from node1
[hadoop@node1 ~]$ exit
logout
Connection to 192.168.193.140 closed.
?

配置hadoop伪分布式

进入hadoop配置目录

cd ${HADOOP_HOME}/etc/hadoop

[hadoop@node1 soft]$ cd ${HADOOP_HOME}/etc/hadoop
[hadoop@node1 hadoop]$ 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hadoop-env.sh

[hadoop@node1 hadoop]$ nano hadoop-env.sh 

配置JAVA_HOME

export JAVA_HOME=/home/hadoop/soft/jdk

配置core-site.xml, 在<configuration>与</configuration>之间添加如下配置

 ? ? ? ?<property>
 ? ? ? ? ? ? ? ?<name>fs.defaultFS</name>
 ? ? ? ? ? ? ? ?<value>hdfs://node1:8020</value>
 ? ? ? ? ? ? ? ?<!-- 以上主机名node1要按实际情况修改 -->
 ? ? ? ?</property>
 ? ? ? ?<property>
 ? ? ? ? ? ? ? ?<name>hadoop.tmp.dir</name>
 ? ? ? ? ? ? ? ?<value>/home/hadoop/soft/hadoop/tmp</value>
 ? ? ? ?</property>
?

配置hdfs-site.xml

同样在<configuration>与</configuration>之间添加配置内容如下：

 ? ? ? ?<property>
 ? ? ? ? ? ? ? ?<name>dfs.replication</name>
 ? ? ? ? ? ? ? ?<value>1</value>
 ? ? ? ?</property>

复制模板文件mapred-site.xml.template为mapred-site.xml

[hadoop@node1 hadoop]$ cp mapred-site.xml.template mapred-site.xml

配置mapred-site.xml

同样在<configuration>与</configuration>之间添加配置内容如下：

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

以上设置了mapreduce运行在yarn框架之上。

配置yarn-site.xml

同样在<configuration>与</configuration>之间添加配置内容如下：

 ? ?<property>
 ? ? ? ?<name>yarn.resourcemanager.hostname</name>
 ? ? ? ?<value>node1</value>
 ? ?</property>
 ? ?<property>
 ? ? ? ?<name>yarn.nodemanager.aux-services</name>
 ? ? ? ?<value>mapreduce_shuffle</value>
 ? ?</property>

配置slaves

配置从节点所在的机器

nano slaves

将localhost修改为主机名，例如: node1

node1

格式化文件系统

hdfs namenode -format

[hadoop@node1 hadoop]$ hdfs namenode -format
22/03/08 06:31:01 INFO namenode.NameNode: STARTUP_MSG: 
/************************************************************
STARTUP_MSG: Starting NameNode
STARTUP_MSG: ? host = node1/192.168.193.140
STARTUP_MSG: ? args = [-format]
STARTUP_MSG: ? version = 2.7.3
STARTUP_MSG: ? classpath = /home/hadoop/soft/hadoop-2.7.3/etc/hadoop:/home/hadoop/soft/hadoop-2.7.3/share/hadoop/common/lib/jaxb-impl-2.2.3-1.jar:/home/hadoop/soft/hadoop-
...
2.7.3/share/hadoop/mapreduce/hadoop-mapreduce-client-hs-plugins-2.7.3.jar:/home/hadoop/soft/hadoop-2.7.3/share/hadoop/mapreduce/hadoop-mapreduce-examples-2.7.3.jar:/home/hadoop/soft/hadoop-2.7.3/share/hadoop/mapreduce/hadoop-mapreduce-client-jobclient-2.7.3-tests.jar:/home/hadoop/soft/hadoop/contrib/capacity-scheduler/*.jar
STARTUP_MSG: ? build = https://git-wip-us.apache.org/repos/asf/hadoop.git -r baa91f7c6bc9cb92be5982de4719c1c8af91ccff; compiled by 'root' on 2016-08-18T01:41Z
STARTUP_MSG: ? java = 1.8.0_271
************************************************************/
22/03/08 06:31:01 INFO namenode.NameNode: registered UNIX signal handlers for [TERM, HUP, INT]
22/03/08 06:31:01 INFO namenode.NameNode: createNameNode [-format]
Formatting using clusterid: CID-911f3db2-a66f-4748-a2bd-bb427d00f2e4
22/03/08 06:31:01 INFO namenode.FSNamesystem: No KeyProvider found.
22/03/08 06:31:01 INFO namenode.FSNamesystem: fsLock is fair:true
22/03/08 06:31:01 INFO blockmanagement.DatanodeManager: dfs.block.invalidate.limit=1000
22/03/08 06:31:01 INFO blockmanagement.DatanodeManager: dfs.namenode.datanode.registration.ip-hostname-check=true
22/03/08 06:31:01 INFO blockmanagement.BlockManager: dfs.namenode.startup.delay.block.deletion.sec is set to 000:00:00:00.000
22/03/08 06:31:01 INFO blockmanagement.BlockManager: The block deletion will start around 2022 Mar 08 06:31:01
22/03/08 06:31:01 INFO util.GSet: Computing capacity for map BlocksMap
22/03/08 06:31:01 INFO util.GSet: VM type ? ? ? = 64-bit
22/03/08 06:31:01 INFO util.GSet: 2.0% max memory 889 MB = 17.8 MB
22/03/08 06:31:01 INFO util.GSet: capacity ? ?  = 2^21 = 2097152 entries
22/03/08 06:31:02 INFO blockmanagement.BlockManager: dfs.block.access.token.enable=false
22/03/08 06:31:02 INFO blockmanagement.BlockManager: defaultReplication ? ? ? ? = 1
22/03/08 06:31:02 INFO blockmanagement.BlockManager: maxReplication ? ? ? ? ? ? = 512
22/03/08 06:31:02 INFO blockmanagement.BlockManager: minReplication ? ? ? ? ? ? = 1
22/03/08 06:31:02 INFO blockmanagement.BlockManager: maxReplicationStreams ? ?  = 2
22/03/08 06:31:02 INFO blockmanagement.BlockManager: replicationRecheckInterval = 3000
22/03/08 06:31:02 INFO blockmanagement.BlockManager: encryptDataTransfer ? ? ?  = false
22/03/08 06:31:02 INFO blockmanagement.BlockManager: maxNumBlocksToLog ? ? ? ?  = 1000
22/03/08 06:31:02 INFO namenode.FSNamesystem: fsOwner ? ? ? ? ? ? = hadoop (auth:SIMPLE)
22/03/08 06:31:02 INFO namenode.FSNamesystem: supergroup ? ? ? ?  = supergroup
22/03/08 06:31:02 INFO namenode.FSNamesystem: isPermissionEnabled = true
22/03/08 06:31:02 INFO namenode.FSNamesystem: HA Enabled: false
22/03/08 06:31:02 INFO namenode.FSNamesystem: Append Enabled: true
22/03/08 06:31:02 INFO util.GSet: Computing capacity for map INodeMap
22/03/08 06:31:02 INFO util.GSet: VM type ? ? ? = 64-bit
22/03/08 06:31:02 INFO util.GSet: 1.0% max memory 889 MB = 8.9 MB
22/03/08 06:31:02 INFO util.GSet: capacity ? ?  = 2^20 = 1048576 entries
22/03/08 06:31:02 INFO namenode.FSDirectory: ACLs enabled? false
22/03/08 06:31:02 INFO namenode.FSDirectory: XAttrs enabled? true
22/03/08 06:31:02 INFO namenode.FSDirectory: Maximum size of an xattr: 16384
22/03/08 06:31:02 INFO namenode.NameNode: Caching file names occuring more than 10 times
22/03/08 06:31:02 INFO util.GSet: Computing capacity for map cachedBlocks
22/03/08 06:31:02 INFO util.GSet: VM type ? ? ? = 64-bit
22/03/08 06:31:02 INFO util.GSet: 0.25% max memory 889 MB = 2.2 MB
22/03/08 06:31:02 INFO util.GSet: capacity ? ?  = 2^18 = 262144 entries
22/03/08 06:31:02 INFO namenode.FSNamesystem: dfs.namenode.safemode.threshold-pct = 0.9990000128746033
22/03/08 06:31:02 INFO namenode.FSNamesystem: dfs.namenode.safemode.min.datanodes = 0
22/03/08 06:31:02 INFO namenode.FSNamesystem: dfs.namenode.safemode.extension ? ? = 30000
22/03/08 06:31:02 INFO metrics.TopMetrics: NNTop conf: dfs.namenode.top.window.num.buckets = 10
22/03/08 06:31:02 INFO metrics.TopMetrics: NNTop conf: dfs.namenode.top.num.users = 10
22/03/08 06:31:02 INFO metrics.TopMetrics: NNTop conf: dfs.namenode.top.windows.minutes = 1,5,25
22/03/08 06:31:02 INFO namenode.FSNamesystem: Retry cache on namenode is enabled
22/03/08 06:31:02 INFO namenode.FSNamesystem: Retry cache will use 0.03 of total heap and retry cache entry expiry time is 600000 millis
22/03/08 06:31:02 INFO util.GSet: Computing capacity for map NameNodeRetryCache
22/03/08 06:31:02 INFO util.GSet: VM type ? ? ? = 64-bit
22/03/08 06:31:02 INFO util.GSet: 0.029999999329447746% max memory 889 MB = 273.1 KB
22/03/08 06:31:02 INFO util.GSet: capacity ? ?  = 2^15 = 32768 entries
22/03/08 06:31:02 INFO namenode.FSImage: Allocated new BlockPoolId: BP-568726822-192.168.193.140-1646692262515
22/03/08 06:31:02 INFO common.Storage: Storage directory /home/hadoop/soft/hadoop/tmp/dfs/name has been successfully formatted.
22/03/08 06:31:02 INFO namenode.FSImageFormatProtobuf: Saving image file /home/hadoop/soft/hadoop/tmp/dfs/name/current/fsimage.ckpt_0000000000000000000 using no compression
22/03/08 06:31:02 INFO namenode.FSImageFormatProtobuf: Image file /home/hadoop/soft/hadoop/tmp/dfs/name/current/fsimage.ckpt_0000000000000000000 of size 353 bytes saved in 0 seconds.
22/03/08 06:31:02 INFO namenode.NNStorageRetentionManager: Going to retain 1 images with txid >= 0
22/03/08 06:31:02 INFO util.ExitUtil: Exiting with status 0
22/03/08 06:31:02 INFO namenode.NameNode: SHUTDOWN_MSG: 
/************************************************************
SHUTDOWN_MSG: Shutting down NameNode at node1/192.168.193.140
************************************************************/
[hadoop@node1 hadoop]$ 
?

若能看到Exiting with status 0，则格式化成功

注意：格式化只需要做一次，格式化成功后，以后就不能再次格式化了。

启动hdfs

start-dfs.sh

验证

jps查看hdfs进程，hdfs进程包括：NameNode、DataNode、SecondaryNameNode

[hadoop@node1 hadoop]$ jps
1989 NameNode
2424 Jps
2300 SecondaryNameNode
2125 DataNode
?

如果少进程，可以切换到$HADOOP_HOME/logs目录，查看对应进程的log文件排查原因，例如：缺少DataNode，应该查看的DataNode的log文件，查看log报的错误、警告、异常信息（Error、Warning、Exception），找到少进程的原因，并解决。

浏览器验证ip:50070，例如：192.168.193.140:50070

启动yarn

start-yarn.sh

验证

jps查yarn进程，yarn进程包括：ResourceManager和NodeManager

[hadoop@node1 hadoop]$ jps
2706 NodeManager
1989 NameNode
2885 Jps
2475 ResourceManager
2300 SecondaryNameNode
2125 DataNode

如果少进程，同样可查看相关log文件来排查。

浏览器访问ip:8088 例如：192.168.193.140:8088

完成！enjoy it!