linux脚本实现双机热备,Keepalived 实现双机热备

原理

首先有一个虚拟ip暴露给客户端，虚拟ip对应的mac地址为一台真实服务器，即用户向虚拟ip发送一个请求，该请求会被分发到真实服务器上。

现在有2台真实服务器，一台master，一台backup，master和backup上都运行着keepalived，当master挂了的时候，backup检测之后，自己成为master,且arp缓存虚拟ip对应的mac地址将变为backup的mac地址，这样请求虚拟ip的报文会被发送到backup

架构图如下：

安装

主机：192.168.1.227

备机：192.168.1.246

虚拟ip：192.168.1.99

安装命令：

wget http://www.keepalived.org/software/keepalived-1.2.13.tar.gz

tar -zxvf keepalived-1.2.13.tar.gz

cd keepalived-1.2.13

./configure --disable-fwmark --prefix=/usr/local/keepalived

make && make install

整理：

mkdir /etc/keepalived/

cp /usr/local/keepalived/etc/keepalived/keepalived.conf /etc/keepalived/

cp /usr/local/keepalived/etc/rc.d/init.d/keepalived /etc/init.d/

cp /usr/local/keepalived/etc/sysconfig/keepalived /etc/sysconfig/

ln -s /usr/local/keepalived/sbin/keepalived /sbin/

配置：

vi /etc/keepalived/keepalived.conf

Master

! Configuration File for keepalived

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 LVS_DEVEL

}

vrrp_instance VI_1 {

state MASTER

interface eth0

virtual_router_id 51

priority 100

advert_int 1

authentication {

auth_type PASS

auth_pass 1111

}

virtual_ipaddress {

192.168.1.99

}

}

Backup 和master一样，只要修改如下地方：

vrrp_instance VI_1 {

state BACKUP

interface eth0

virtual_router_id 51

priority 99 # 这里改为99，master优先级是100

advert_int 1

authentication {

auth_type PASS

auth_pass 1111

}

virtual_ipaddress {

192.168.1.99

}

}

管理命令：

停止

service keepalived stop

启动

service keepalived start

重启

service keepalived restart

查看状态

service keepalived status

测试

在本机上查看虚拟ip状态

ip add

在同一网段的其他机器上查询arp缓存

arp -a

这里的1.99对应的mac地址是1.227

停掉master的keepalived

service keepalived stop

在同一网段的其他机器上查询arp缓存

arp –a

发现1.99的mac地址已经变为slave的mac地址

那么主备双机热备就完成了

总结：本篇文章实现的功能

1.master主机挂了，或者master 上keepalived挂了之后，可以切换到slave

2.master的网络不通的时候，可以立即切换到slave，但是如果只是master上的应用出现问题的时候，是不会主动切换的，这个要通过编写脚本来监控应用出问题，这个问题后续再讨论吧。

Keepalived 的详细介绍：请点这里

Keepalived 的下载地址：请点这里