之前的博文介绍了如何配置MYSQL双主互备.

见http://www.centoscn.com/mysql/2015/1030/6351.html

这里介绍如何配合前者实现Keepalived双机热备

系统环境：CentOS 6.3 x64

MySQL版本：mysql-5.6.10

Keepalived版本：keepalived-1.2.7

MySQL-VIP：192.168.7.253

MySQL-master1：192.168.7.201

MySQL-master2：192.168.7.249

首先关闭iptables和SELINUX

# service iptables stop

# setenforce 0

# vi /etc/sysconfig/selinux

---------------

SELINUX=disabled

---------------

注: 若线上需要开启iptables,需加一条规则使keepalived的vrrp通行

# iptables -A INPUT -p vrrp -j ACCEPT

1.在MySQL-master1：192.168.7.201服务器上keepalived安装及配置

编译安装，实际以本机kernel版本为准

# wget http://www.keepalived.org/software/keepalived-1.2.7.tar.gz

# tar zxvf keepalived-1.2.7.tar.gz

# cd keepalived-1.2.7

# ./configure --prefix=/usr/local/keepalived --with-kernel-dir=/usr/src/kernels/2.6.32-279.el6.x86_64

# make && make install

设置keepalived开机启动脚本

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

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

# cp /usr/local/keepalived/sbin/keepalived /usr/sbin/

# chkconfig keepalived on

新建一个配置文件，默认keepalived启动会去/etc/keepalived目录下寻找配置文件

# mkdir /etc/keepalived

# vi /etc/keepalived/keepalived.conf

------------------

global_defs {

notification_email {

lzyangel@126.com

}

#当主、备份设备发生改变时，通过邮件通知

notification_email_from lzyangel@126.com

smtp_server stmp.126.com

smtp_connect_timeout 30

router_id MySQL-ha

}

vrrp_instance VI_1{

# 在初始化状态下定义为主设备

state BACKUP

# 注意网卡接口

interface eth0

virtual_router_id 51

# 优先级，另一台改为90

priority 100

advert_int 1

# 不主动抢占资源

nopreempt

authentication {

# 认证方式，可以是PASS或AH两种认证方式

auth_type PASS

# 认证密码

auth_pass 1111

}

virtual_ipaddress {

# 虚拟IP地址，随着state的变化而增加删除

192.168.7.253

}

}

virtual_server 192.168.7.253 3306 {

# 每个2秒检查一次real_server状态

delay_loop 2

# LVS算法

lb_algo wrr

# LVS模式

lb_kind DR

# 会话保持时间

persistence_timeout 60

protocol TCP

real_server 192.168.7.201 3306 {

# 权重

weight 3

# 检测到服务down后执行的脚本

notify_down /etc/rc.d/keepalived.sh

TCP_CHECK {

# 连接超时时间

connect_timeout 10

# 重连次数

nb_get_retry 3

# 重连间隔时间

delay_before_retry 3

# 健康检查端口

connect_port 3306

}

}

}

----------------------

编写检测服务down后所要执行的脚本

# vi /etc/rc.d/keepalived.sh

-------------

#!/bin/sh

/etc/init.d/keepalived stop

-------------

# chmod +x /etc/rc.d/keepalived.sh

注：此脚本是上面配置文件notify_down选项所用到的，keepalived使用notify_down选项来检查real_server的服务状态。

当发现real_server服务故障时，便触发此脚本.

我们可以看到，脚本就一个命令:

通过pkill keepalived强制杀死keepalived进程，从而实现了MySQL故障自动转移.

另外，我们不用担心两个MySQL会同时提供数据更新操作，因为每台MySQL上的keepalived的配置里面只有本机MySQL的IP+VIP，而不是两台MySQL的IP+VIP.

以上脚本是为了在测试环境实现VIP切换功能，生产环境建议使用如下脚本

---------------------------------

#!/bin/bash

# 环境变量

PATH=/bin:/usr/bin:/sbin:/usr/sbin; export PATH

# 暂停5秒执行，防止数据库人工正常重启

sleep 5

# mysql_id(存活=1 死掉=0)

mysql_id=`ps -C mysqld --noheader |wc -l`

# 判断mysql_id若死掉，则重启mysql一次，若仍然无法启动mysql则杀掉keepaliaved进程实现VIP切换

if [ $mysql_id -eq 0 ];then

/etc/init.d/mysqld restart

sleep 5

if [ $mysql_id -eq 0 ];then

/etc/init.d/keepalived stop

fi

fi

---------------------------------

启动keepalived

# /etc/init.d/keepalived start

查看连接状态

# ps -aux | grep keepalived

返回：

---------------

root 1387 1 0 21:13 ? 00:00:00 keepalived -D

root 1390 1387 0 21:13 ? 00:00:00 keepalived -D

root 1391 1387 0 21:13 ? 00:00:00 keepalived -D

root 1976 1911 0 21:16 pts/0 00:00:00 grep keepalived

--------------------

测试

查看VIP信息

# ip addr

--------------------------

............

inet 192.168.7.201/24 brd 192.168.7.255 scope global eth0

inet 192.168.7.253/32 scope global eth0

inet6 fe80::20c:29ff:feb2:9199/64 scope link

valid_lft forever preferred_lft forever

--------------------------

注:如果出现主从在切换VIP时，主的VIP未自动关闭，从的正常开启，导致都获取到VIP，造成互相冲突的情况，可手动输入如下命令删除一方的VIP地址

# ip addr del "虚拟ip" dev eth0

但此方法只是一个临时的解决方案，当手动删除VIP后，重启keepalived服务会无法正常开启vip，需要重启服务器方能恢复。

查看vrrp通信

# tcpdump vrrp

-------------------------

.....

18:10:56.365730 IP 192.168.7.201 > vrrp.mcast.net: VRRPv2, Advertisement, vrid 52, prio 40, authtype simple, intvl 1s, length 20

18:10:57.366825 IP 192.168.7.201 > vrrp.mcast.net: VRRPv2, Advertisement, vrid 52, prio 40, authtype simple, intvl 1s, length 20

18:10:58.367914 IP 192.168.7.201 > vrrp.mcast.net: VRRPv2, Advertisement, vrid 52, prio 40, authtype simple, intvl 1s, length 20

-------------------------

注:如果主keepalived挂掉，这里的日志会切换到备keeplived的信息

找一台局域网PC，然后去ping MySQL的VIP，这时候MySQL的VIP是可以ping的通的

停止MySQL服务，看keepalived健康检查程序是否会触发我们编写的脚本,去kill掉keepalived进程

# service mysqld stop

# ps -aux | grep keepalived

无返回结果

2.在MySQL-master2：192.168.7.249服务器上keepalived安装及配置

编译安装，实际以本机kernel版本为准

# wget http://www.keepalived.org/software/keepalived-1.2.7.tar.gz

# tar zxvf keepalived-1.2.7.tar.gz

# cd keepalived-1.2.7

# ./configure --prefix=/usr/local/keepalived --with-kernel-dir=/usr/src/kernels/2.6.32-279.el6.x86_64

# make && make install

设置keepalived开机启动脚本

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

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

# cp /usr/local/keepalived/sbin/keepalived /usr/sbin/

# chkconfig keepalived on

新建一个配置文件，默认keepalived启动会去/etc/keepalived目录下寻找配置文件

# mkdir /etc/keepalived

# vi /etc/keepalived/keepalived.conf

------------------

global_defs {

notification_email {

lzyangel@126.com

}

notification_email_from lzyangel@126.com

smtp_server stmp.126.com

smtp_connect_timeout 30

router_id MySQL-ha

}

vrrp_instance VI_1{

# 两台配置此处均是BACKUP

state BACKUP

# 注意网卡接口

interface eth0

virtual_router_id 51

# 优先级，另一台改为100

priority 90

advert_int 1

# 不主动抢占资源

nopreempt

authentication {

auth_type PASS

auth_pass 1111

}

virtual_ipaddress {

192.168.7.253

}

}

virtual_server 192.168.7.253 3306 {

# 每个2秒检查一次real_server状态

delay_loop 2

# LVS算法

lb_algo wrr

# LVS模式

lb_kind DR

# 会话保持时间

persistence_timeout 60

protocol TCP

real_server 192.168.7.249 3306 {

weight 3

# 检测到服务down后执行的脚本

notify_down /etc/rc.d/keepalived.sh

TCP_CHECK {

# 连接超时时间

connect_timeout 10

# 重连次数

nb_get_retry 3

# 重连间隔时间

delay_before_retry 3

# 健康检查端口

connect_port 3306

}

}

}

----------------------

编写检测服务down后所要执行的脚本

# vi /etc/rc.d/keepalived.sh

-------------

#!/bin/sh

/etc/init.d/keepalived stop

-------------

# chmod +x /etc/rc.d/keepalived.sh

启动keepalived

# /etc/init.d/keepalived start

查看连接状态

# ps -aux | grep keepalived

返回：

---------------

root 1387 1 0 21:13 ? 00:00:00 keepalived -D

root 1390 1387 0 21:13 ? 00:00:00 keepalived -D

root 1391 1387 0 21:13 ? 00:00:00 keepalived -D

root 1976 1911 0 21:16 pts/0 00:00:00 grep keepalived

--------------------

至此配置完成，网站后台只需要配置MySQL-VIP：192.168.7.253虚拟地址即可

这里实际连接的master数据库，以哪台master先开mysql服务为准。

当master1：192.168.7.201 mysql端口挡掉或者服务器异常关闭，keepalived会自动跳转到master2：192.168.7.249.

因为两台数据库的数据时同步的,用户访问的是MySQL-VIP：192.168.7.253虚拟地址，所以网站数据连接会无缝透明转接到master2服务

器，实现双机热备+数据同步功能。保证网站数据库的实时可用性。

注：当某一台master服务器挂掉恢复后，需同时打开MYSQL服务和keepalived服务，保证另一台服务器如果挂掉会无缝转接。

所以建议mysql与keeplived设置服务开机启动。

# chkconfig mysqld on

# chkconfig keepalived on

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