Linux Web集群架构详细(亲测可用!!!)

Linux Web集群架构详细(亲测可用!!!)_第1张图片

 

 

 

 

注意:WEB服务器和数据库需要分离,同时WEB服务器也需要编译安装MySQL。

做集群架构的重要思想就是找到主干,从主干区域向外延展。

 

WEB服务器: apache nginx  本地做三个产品 dedecms workprocess discuz 将用户存放图片,附件的目录挂载到nfs服务器的共享目录上

NFS服务器 本地做三个共享目录,实现将用户上传的图片及附件分别存放到对应的目录上,

使用sersync与备份服务器实现实时同步,批量分发密钥及脚本,hosts文件(实际生产环境下,在同一局域网下,hosts文件通常保持一致),

MySQL服务器:用于用户存放数据的服务器,

Backup服务器:用于备份的服务器,防止其他服务器宕机、感染病毒、等等数据丢失。同时要将每天备份的内容通过邮件发送给管理员,确保数据备份成功。

 

我的主干思想就是先配置LAMP和LNMP服务器,之后向外延展配置nfs服务器及MySQL服务器,然后将所有需要备份的数据打包好,配置backu备份服务器,最后做nginx负载均衡服务器,如果有精力又有能力的情况下,继续延伸一个nginx的高可用(提示ngixn高可用服务使用的是VRRP技术)

1.LAMP(192.168.190.20)

(1)tar xvf /apache-2.2.27

cd apache-2.2.27

编译安装

./configure \

--prefix=/application/appache2.2.27 \   安装目录

--enable-deflate \   压缩安装

--enable-expires \    过期  缓存时间

--enable-headers \   

--enable-modules=most \    模块激活

--enable-so \     

--with-mpm=worker \   apache的两种模式:worker,prefork

--enable-rewrite && make &&make install

(注意编译环境下换行后边不能存在空格,上述编译添加了注释,如果粘贴请自行删除,手打忽略)

 

ln -s /application/apache-2.2.27 /application/apache

echo “

 a ,s blog. 



        Hi,i'm a ,My blog address is

 



” > /application/apache/htdos/index.html

/application/apache/bin/apachectl graceful

浏览器输入192.168.190.20 会出现

Hi,i'm a ,My blog address is 等字样说明apache服务安装成功

 

(2)安装数据库msyql

解压编译安装    ,编译过程略长,安装结束后进行检查做软链接

创建MySQL虚拟用户和用户组

groupadd mysql

  cat /etc/group

  useradd -g mysql -M -s /sbin/nologin mysql

id mysql

编译安装MySQL

./configure \

--prefix=/application/mysql5.1.72 \

--with-unix-socket-path=/application/mysql5.1.72/tmp/mysql.sock \

--localstatedir=/application/mysql5.1.72/data \

--enable-assembler \

--enable-thread-safe-client \

--with-mysqld-user=mysql \

--with-big-tables \

--without-debug \

--with-pthread \

--enable-assembler \

--with-extra-charsets=complex \

--with-readline \

--with-ssl \

--with-embedded-server \

--enable-local-infile \

--with-plugins=partition,innobase \

--with-mysqld-ldflags=-all-static \

--with-client-ldflags=-all-static

#--with-plugin-PLUGIN \

make && make install

echo $?  检查编译是否成功

ln -s /application/mysql5.1.72/ /application/mysql    创建软链接

复制配置mysql的配置文件

cd  mysql-5.1.72/support-files/

ls

cp -p my-small.cnf /etc/my.cnf

chown -R mysql.mysql /application/mysql    授权MySQL用户管理权限

初始化mysql

/application/mysql/bin/mysql_install_db --basedir=/application/mysql --datadir=/application/mysql/data/ --user=mysql           ##两个OK即为初始化成功

/application/mysql/bin/mysqld_safe &    启动mysql

netstat -lntup|grep mysqld       ##查看MySQL服务是否启动成功

mysqladmin -u root password '123456'        ##设置MySQL用户密码

(3)安装完apache和mysql之后再安装PHP(注意php配合apache是以模块的方式存在)

yum install -y openssl-devel

tar -xvf  php-5.3.27.tar.gz

cd php-5.3.27.tar.gz

./configure \

--prefix=/application/php5.3.27 \     //注意php的安装目录

--with-apxs2=/application/apache/bin/apxs \        //注意apache的安装目录

--with-mysql=/application/mysql \

--with-xmlrpc \

--with-openssl \

--with-zlib \

--with-freetype-dir \

--with-gd \

--with-jpeg-dir \

--with-png-dir \

--with-iconv=/usr/local/libiconv \

--enable-short-tags \

--enable-sockets \

--enable-zend-multibyte \

--enable-soap \

--enable-mbstring \

--enable-static \

--enable-gd-native-ttf \

--with-curl \

--with-xsl \

--enable-ftp \

--with-libxml-dir && make && make install
ln -s /application/php5.3.27/ /application/php  ##做软链接去版本号

cp /application/apache/conf/httpd.conf /application/apache/conf/httpd.conf.bak.1

vim /application/apache/conf/httpd.conf       #修改主配置文件

cd /application/apache/conf

diff  httpd.conf httpd.conf.bak.1

67,68c67,68

< User www

< Group www

---

> User daemon

> Group daemon

149c149

<     DirectoryIndex  index.php index.html

---

>     DirectoryIndex  index.html

292,294c292

<     AddType application/x-httpd-php .php .phtml

<     AddType application/x-httpd-php-source .phps

---

> 

401c401

< Include conf/extra/httpd-vhosts.conf

---

># Include conf/extra/httpd-vhosts.conf:

423 

424     Options -Indexes FollowSymLinks

425     AllowOverride None

426     Order allow,deny

427     Allow from all

428 

创建对应的apache的虚拟用户www

useradd www -s /sbin/nologin -M

id www     

cd /application/apache/conf/extra

vim httpd-vhosts.conf

NameVirtualHost *:80

#

# VirtualHost example:

# Almost any Apache directive may go into a VirtualHost container.

# The first VirtualHost section is used for all requests that do not

# match a ServerName or ServerAlias in any  block.

#



    ServerAdmin [email protected]

    DocumentRoot "/data0/www/cms"

    ServerName cms.etiantian.org

    ServerAlias etiantian.org

    ErrorLog "logs/dummy-host.example.com-error_log"

    CustomLog "|/usr/local/sbin/cronolog /app/logs/access_cms_%Y%m%d.log" combined





    ServerAdmin [email protected]

    DocumentRoot "/data0/www/bbs"

    ServerName bbs.etiantian.org

    ErrorLog "logs/dummy-host.example.com-error_log"

    CustomLog "|/usr/local/sbin/cronolog /app/logs/access_bbs_%Y%m%d.log" combined





    ServerAdmin [email protected]

    DocumentRoot "/data0/www/blog"

    ServerName blog.etiantian.org

    ErrorLog "logs/dummy-host.example.com-error_log"

    CustomLog "|/usr/local/sbin/cronolog /app/logs/access_blog_%Y%m%d.log" combined

如果有错误则查看错误日志

cd /application/appache/logs/

建立站点目录

mkdir /data0/{www,blog,bbs}

for n in www blog bbs ;do echo "$n.etiantian.org" > /data0/$n/index.html;done

/application/apache/bin/apachectl -t        #检查配置文件的语法

/application/apache/bin/apachectl graceful     #平滑重启apache

本地做hosts解析  访问三个网站  ,查看基于域名的虚拟主机是否配置成功

Dedecms,Discuz,workprocess三个产品解压之后自行安装(安装完MySQL数据库再进行安装)

2.LNMP(192.168.190.10)

(1)安装nginx服务

编译nginx前  需安装

1.pcre pcre-devel

yum install -y pcre pcre-devel

2.openssl

yum install openssl openssl-devel -y

编译安装nginx

./configure --user=nginx --group=nginx --prefix=/application/nginx1.6.2 --with-http_stub_status_module --with-http_ssl_module

make && make install

ln -s /application/nginx1.6.2/ /application/nginx

启动nginx

/application/nginx/sbin/nginx

lsof -I :80      #查看nginx服务是否启动成功

(2)安装MySQL数据库

编译安装MySQL

./configure --prefix=/application/mysql5.1.72 --with-unix-socket-path=/application/mysql5.1.72/tmp/mysql.sock --localstatedir=/application/mysql5.1.72/data --enable-assembler 
--enable-thread-safe-client --with-mysqld-user=mysql --with-big-tables --without-debug --with-pthread --enable-assembler --with-extra-charsets=complex --with-readline
--with-ssl --with-embedded-server --enable-local-infile --with-plugins=partition,innobase --with-mysqld-ldflags=-all-static --with-client-ldflags=-all-static make && make install

  

echo $?

数据库初始化:

chown -R mysql.mysql /application/mysql    授权MySQL用户管理权限

初始化mysql

/application/mysql/bin/mysql_install_db --basedir=/application/mysql --datadir=/application/mysql/data/ --user=mysql

//初始化显示两个OK 即为初始化成功

(3)安装PHP(PHP配合nginx是以守护进程的方式存在工作的)

(安装php之前需要安装所需的包 yum install zlib libxml libjpeg freetype libpng gd  curl libiconv  zlib-devel libxml2-devel libjpeg-devel freetype-devel libpng-devel gd-devel curl-devel -y)

tar zxf libiconv-1.14.tar.gz

cd libiconv-1.14

./configure --prefix=/usr/local/libiconv      //然后进行编译安装

make && make install

安装相关依赖

Libmcrypt  、 mhash   、mcrypt

安装php(编译之前首先安装libxslt* ,否则会报错)  解压

./configure --prefix=/application/php5.3.27 --with-mysql=/application/mysql --with-iconv-dir=/usr/local/libiconv --with-freetype-dir --with-jpeg-dir --with-png-dir --with-zlib 
--with-libxml-dir=/usr --enable-xml --disable-rpath --enable-safe-mode --enable-bcmath --enable-shmop --enable-sysvsem --enable-inline-optimization --with-curl
--with-curlwrappers --enable-mbregex --enable-fpm --enable-mbstring --with-mcrypt --with-gd --enable-gd-native-ttf --with-openssl --with-mhash --enable-sockets --with-xmlrpc
--enable-zip --enable-soap --enable-short-tags --enable-zend-multibyte --enable-static --with-xsl --with-fpm-user=nginx --with-fpm-group=nginx --enable-ftp && make && make install

  

上传修改好的启动文件php-frm.conf(软件包组里面有修改完整的) à上传到/application/php/etc

创建日志文件

mkdir /app/logs    //不创建的话检查语法的时候会报错

/application/php/sbin/php-fpm -t   //检查语法

/application/php/sbin/php-fpm    //启动php

在rc.local里设置开机自启动

Mysql php nginx

 

##优化配置文件

cat /application/nginx/conf/

cat nginx.conf

worker_processes  1;

events {

    worker_connections  1024;

}

http {

    include       mime.types;

    default_type  application/octet-stream;

    sendfile        on;

    keepalive_timeout  65;

        include extra/cms.conf;

        include extra/bbs.conf;

        include extra/blog.conf;

}

mdkir extra

touch {bbs,blog,cms}.conf

cat cms.conf

server {

        listen       80;

        server_name  cms.etiantian.org;

            root   /data0/www/cms;

            index index.php index.html index.htm;

        location ~ \.(php|php5)?$ {

        fastcgi_pass 127.0.0.1:9000;

        fastcgi_index index.php;

        include fastcgi.conf;

        }

}

cat bbs.conf

server {

        listen       800;

        server_name  bbs.etiantian.org;

            root   /data0/www/bbs;

            index index.php index.html index.htm;

        location ~ \.(php|php5)?$ {

        fastcgi_pass 127.0.0.1:9000;

        fastcgi_index index.php;

        include fastcgi.conf;

        }

}

cat blog,conf

server {

        listen       8000;

        server_name  blog.etiantian.org;

                    root   /data0/www/blog;

            index  index.php index.html index.htm;

  location ~ \.(php|php5)?$ {

        fastcgi_pass 127.0.0.1:9000;

        fastcgi_index index.php;

        include fastcgi.conf;      

 }

}

mkdir /data0/{www,blog,bbs}

for n in www blog bbs ;do echo "$n.etiantian.org" > /data0/$n/index.html;done

Discuz,dedecms,workprocess三个产品自行安装放入站点目录 bbs,www,blog

3.NFS服务器(192.168.190.30)

(1)安装nfs和rpcbind(nfs服务是靠rpcbind转发端口的)

yum install nfs-utils rpcbind -y

echo “/etc/init.d/nfs restart” >/etc/rc.local     //设置nfs开机自启动使用chkconfig同样

vim /etc/exports

#shared storage for LAMP,LNMP

/data0 192.168.190.10(rw,async) 192.168.190.20(rw.async)

(2)批量分发

ssh-copy-id -i   是可以实现小环境下的密钥分发但是如果上百台服务器,就需要开发脚本进行自动化分发密钥(附件里有开发好的脚本,仅供参考)

密钥分发完毕,分发本地的hosts文件(实际生产环境下统一内网下,hosts本地解析一致是很有必要的)

vim /etc/rsync.password

123456

chmod 600 /etc/rsync.password

(3)sersync实现与备份备份服务器的实时同步

安装sersync

cd /tools

uzip sersync2.5.4_64bit_binary_stable_final.tar

mv sersync2 /usr/local/sersync

cd /usr/local/sersync/conf

echo ‘export PATH=$PATH:/usr/local/sersync/bin’ >>/etc/profile

vim /usr/local/sersync/conf/www_confxml.xml (需要哪个目录rsync服务器同步就写哪个目录,这里以博客workprocess为例name代表rsync服务端的模块名称 ip就是目标IP地址)

24 

 25         

 26 

echo ‘sersync -r -d -o /usr/local/sersync/conf/www_confxml.xml’ >> /etc/rc.local

至此sersync与备份服务器实时同步也完成了。

 

4.安装MySQL服务器(192.168.190.40),创建你所做的产品的数据库,创建每个产品所使用的数据库用户,及授权用户。

创建MySQL虚拟用户 useradd -g mysql -M -s /sbin/nologin mysql

(1)编译安装MySQL数据库

tar xvf mysql5.1.72.tar.gz

cd mysql5.1.72

./configure --prefix=/application/mysql5.1.72 --with-unix-socket-path=/application/mysql5.1.72/tmp/mysql.sock --localstatedir=/application/mysql5.1.72/data --enable-assembler
--enable-thread-safe-client --with-mysqld-user=mysql --with-big-tables --without-debug --with-pthread --enable-assembler --with-extra-charsets=complex --with-readline
--with-ssl --with-embedded-server --enable-local-infile --with-plugins=partition,innobase --with-mysqld-ldflags=-all-static --with-client-ldflags=-all-static
ln -s /application/mysql5.1.72/ /application/mysql

/application/mysql/bin/mysql_install_db --basedir=/application/mysql --datadir=/application/mysql/data/ --user=mysql   ##初始化数据库

cd /tools/msyql5.1.71

\cp support-files/mysql.server /etc/init.d/mysqld

/etc/init.d/mysqld start

netstat -lntup |grep mysql        #查看MySQL3306端口是否开启

mysqladmin -u root password '123456'      ## 设置数据库用户名和密码

(2)进入数据库创建用户并进行授权,创建用户所用的数据库cms bbs blog

mysql -uroot -p123456

mysql> create database bbs;

mysql> create database cms;

mysql> create database blog;

mysql> show databases;       ##查看数据库

mysql> grant select,insert,update,delete,alter,create on cms.* to  cms@"192.168.190.%" identified by '123456';

mysql> grant select,insert,update,delete,alter,create on bbs.* to  bbs@'192.168.190.%' identified by '123456';

mysql> grant select,insert,update,delete,alter,create on blog.* to  blog@'192.168.190.%' identified by '123456';

mysql> select user,host from mysql.user;       ##查看用户是否创建成功

(3)MySQL数据库数据备份,利用周期性计划任务定时推送(简单的备份使用mysqldump,高层的备份服务使用replication或者drbd)

[root@mysql scripts]# cat mysqldunmp.sh

!#bin/bash

cd /backup

echo "You are in backup dir"

File = /backup/

mysqldump -uroot -p123456 --quick --databases bbs blog cms --flush-logs --single-transaction > /backup/mysql$(date +%F).bak

rsync -az /backup/mysql* [email protected]::mysql --password-file=/etc/rsync.password

echo "Your database backup successfully completed"

vim /etc/rsync.password

123456

chmod 600 /etc/rsync.password

crontab -e

#send mysqlbak

00 00 * * * /bin/sh -x /server/script/mysqldump.sh

5.backup服务器(192.168.190.40 rsync ,每天检查推送过来的备份内容,定时发送邮件告知系统管理员备份是否成功)

useradd -s /sbin/nologin rsync            创建rsync 用户

yum install -y rsync

echo "/usr/bin/rsync --daemon" >> /etc/rc.local

 

vim /etc/rsyncd.conf

##rsyncd.conf start##

uid = rsync

gid = rsync

use chroot = no

max connections = 200

timeout = 300

pid file = /var/run/rsyncd.pid

lock file = /var/run/rsync.lock

log file = /var/log/rsyncd.log

ignore errors

read only = false

list = false

hosts allow = 10.0.0.0/24

hosts deny = 0.0.0.0/32

auth users = rsync_backup

secrets file = /etc/rsync.password

[zhang]

path = /zhang/

[cms]

path =/data0/www/cms/

[bbs]

path =/data0/www/bbs/

[blog]

path =/data0/www/blog/

[backup]

path =/backup/

[nfs]

path =/backup/nfs/

[mysql]

path =/mysql/

所有的推送文件夹必须存在 ,否则rsync启动会报错

chown -R rsync.rsync   /zhang/

chown -R rsync.rsync  /data0/www/cms/

chown -R rsync.rsync  /data0/www/bbs/

chown -R rsync.rsync  /data0/www/blog/

chown -R rsync.rsync  /backup/

chown -R rsync.rsync  /backup/nfs/

chown -R rsync.rsync  /mysql/

vim /etc/rsync.password

rsync_backup:123456

chmod 600 /etc/rsync.password

echo “/usr/bin/rsync --daemon” >> /etc/rc.local

 

vim /server/script/check.sh

ls /mysql >> /root/check.txt

ls -l /backup/192.168.190.30/|awk '{print $9}' >> /root/check.txt

egrep -v "^$| " /root/check.txt > /root/checkadd.txt

最后推送checkadd.txt文本文档给系统管理员  管理员就可以看到都备份了什么文件

mail -s "Hello from linuxde.net by file" [email protected] < checkadd.txt

 

6.主nginx负载均衡服务器(192.168.190.23)

(1)安装配置nginx负载均衡器

编译nginx前  需安装

1.pcre pcre-devel

yum install -y pcre pcre-devel

2.openssl

yum install openssl openssl-devel -y

##创建nginx的虚拟用户

usedadd nginx -s /sbin/nologin -M

编译安装nginx

./configure --user=nginx --group=nginx --prefix=/application/nginx1.6.2 --with-http_stub_status_module --with-http_ssl_module

make && make install

ln -s /application/nginx1.6.2/ /application/nginx

##启动nginx

/application/nginx/sbin/nginx

vim /application/nginx/conf/nginx.conf

worker_processes  1;

events {

    worker_connections  1024;

}

http {

    include       mime.types;

    default_type  application/octet-stream;

    sendfile        on;

    keepalive_timeout  65;

 

upstream backend {

        ip_hash;

        server 192.168.190.10:80 max_fails=3 fail_timeout=30s;

        server 192.168.190.20:80 max_fails=3 fail_timeout=30s;

}

upstream backendyy {

        server 192.168.190.10:800 max_fails=3 fail_timeout=30s;

        server 192.168.190.20:800 max_fails=3 fail_timeout=30s;

}

upstream backendblog {

        ip_hash;

        server 192.168.190.10:8000 max_fails=3 fail_timeout=30s;

        server 192.168.190.20:8000 max_fails=3 fail_timeout=30s;

}

 

   server {

        listen       80;

        server_name  cms.etiantian.org;

        index  index.html index.htm;

        location / {

        proxy_pass http://backend;

        }

        error_page   500 502 503 504  /50x.html;

        location = /50x.html {

            root   html;

        }

}

       server {

        listen       80;

        server_name  bbs.etiantian.org;

        index  index.html index.htm;

        location / {

        proxy_pass http://backendyy;

        }

        error_page   500 502 503 504  /50x.html;

        location = /50x.html {

            root   html;

        }

    }

 

   server {

        listen       80;

        server_name  blog.etiantian.org;

        index  index.html index.htm;

        location / {

        proxy_pass http://backendblog;

        }

        error_page   500 502 503 504  /50x.html;

        location = /50x.html {

            root   html;

        }

    }

}

平滑重启nginx :/application/nginx/bin/nginx -s reload

(2)安装配置keepalived

yum install -y keepalived

netstat -lntup |grep keepalived

vim /etc/keepalived/keepalived.conf

 

global_defs {

 

   notification_email {

 

     [email protected]

 

     [email protected]

 

     [email protected]

 

   }

 

   notification_email_from [email protected]

 

   smtp_server 192.168.200.1

 

   smtp_connect_timeout 30

 

   router_id lb01

}

vrrp_instance VI_1 {

 

    state MASTER

 

    interface eth1

 

    virtual_router_id 55

 

    priority 150

 

    advert_int 1

 

    authentication {

 

        auth_type PASS

 

        auth_pass 123456

 

    }

 

    virtual_ipaddress {

        192.168.190.23/24 dev eth1 label eth1:1

    }

}

/etc/init.d/keepalived restart     ifconfig会发现生成了一个你想要的虚拟IP地址

7.高可用的备份nginx负载均衡服务器(192.168.190.23)

(1)安装配置nginx负载均衡器

编译nginx前  需安装

1.pcre pcre-devel

yum install -y pcre pcre-devel

2.openssl

yum install openssl openssl-devel -y

编译安装nginx

./configure --user=nginx --group=nginx --prefix=/application/nginx1.6.2 --with-http_stub_status_module --with-http_ssl_module

make && make install

ln -s /application/nginx1.6.2/ /application/nginx

##创建nginx的虚拟用户

usedadd nginx -s /sbin/nologin -M

##启动nginx

/application/nginx/sbin/nginx

vim /application/nginx/conf/nginx.conf

worker_processes  1;

events {

    worker_connections  1024;

}

http {

    include       mime.types;

    default_type  application/octet-stream;

    sendfile        on;

    keepalive_timeout  65;

 

upstream backend {

        ip_hash;

        server 192.168.190.10:80 max_fails=3 fail_timeout=30s;

        server 192.168.190.20:80 max_fails=3 fail_timeout=30s;

}

upstream backendyy {

        server 192.168.190.10:800 max_fails=3 fail_timeout=30s;

        server 192.168.190.20:800 max_fails=3 fail_timeout=30s;

}

upstream backendblog {

        ip_hash;

        server 192.168.190.10:8000 max_fails=3 fail_timeout=30s;

        server 192.168.190.20:8000 max_fails=3 fail_timeout=30s;

}

 

   server {

        listen       80;

        server_name  cms.etiantian.org;

        index  index.html index.htm;

        location / {

        proxy_pass http://backend;

        }

        error_page   500 502 503 504  /50x.html;

        location = /50x.html {

            root   html;

        }

}

       server {

        listen       80;

        server_name  bbs.etiantian.org;

        index  index.html index.htm;

        location / {

        proxy_pass http://backendyy;

        }

        error_page   500 502 503 504  /50x.html;

        location = /50x.html {

            root   html;

        }

    }

 

   server {

        listen       80;

        server_name  blog.etiantian.org;

        index  index.html index.htm;

        location / {

        proxy_pass http://backendblog;

        }

        error_page   500 502 503 504  /50x.html;

        location = /50x.html {

            root   html;

        }

    }

}

平滑重启nginx :/application/nginx/bin/nginx -s reload

(2)安装keepalived

yum install -y keepalived

vim /etc/keepalived/keepalived.conf

global_defs {

 

   notification_email {

 

     [email protected]

 

     [email protected]

 

     [email protected]

 

   }

 

   notification_email_from [email protected]

 

   smtp_server 192.168.200.1

 

   smtp_connect_timeout 30

 

   router_id lb02

 

}

 

 

 

vrrp_instance VI_1 {

 

    state BACKUP

 

    interface eth2

 

    virtual_router_id 55

 

    priority 100       ##优先级  数值越高越优先

 

    advert_int 1

 

    authentication {

 

        auth_type PASS

 

        auth_pass 123456

 

    }

 

    virtual_ipaddress {

 

        192.168.190.23 dev eth2 label eth2:1

    }

}

/etc/init.d/keepalived restart    启动keepalived 把主nginx负载均衡服务器宕掉 ,会发现备keepalived节点服务器会生成一个虚拟IP

本地做192.168.190.23的host解析

 

Keepalived高可用故障切换转移原理

    Keepalived高可用服务对之间的故障切换转移,是通过VRRP来实现的。在keepalived服务工作时,主Master节点会不断地向备节点发送(多播的方式)心跳消息,用来告诉备Backup节点自己还活着。当主节点发生故障时,就无法发送心跳的消息了,备节点也因此无法继续检测到来自主节点的心跳了。于是就会调用自身的接管程序,接管主节点的IP资源和服务。当主节点恢复时,备节点又会释放主节点故障时自身接管的IP资源和服务,恢复到原来的备用角色

 

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