Mysql+keepalived主从切换

一、概述

Keepalived看名字就知道，保持存活，在网络里面就是保持在线了，也就是所谓的高可用或热备，用来防止单点故障（单点故障是指一旦某一点出现故障就会导致整个系统架构的不可用）的发生，那说到keepalived不得不说的一个协议不是VRRP协议，可以说这个协议就是keepalived实现的基础。

二、配置实现mysql+keepalived主从切换

网络结构：

VIP :192.168.1.30

MYSQL A:192.168.1.28

MYSQL B:192.168.1.29

1、mysql主从同步

要实现mysql+keepalived主从切换，首先要实现的就是两台mysql服务器的主从同步。关于主从同步，可以参考之前的文章 http://smalldeng.blog.51cto.com/1038075/1062192

2、安装keepalived

(1)用yum 安装

Yum -y install keepalived

(2)源码安装

#tar zxvf keepalived-1.2.7.tar.gz

#cd keepalived-1.2.7

#./configure

出错：

yum -y install openssl

yum -y install libpopt-dev

yum -y install libssl-dev

yum -y install libssl0.9.8

#make & make install

3、keepalived主备配置文件

下面将详细讲述在MYSQL A服务器上对keepalived的配置。

#vim /etc/keepalived/keepalived.conf

! Configuration File for keepalived

global_defs {

notification_email {

[email protected]

}

notification_email_from [email protected]

smtp_connect_timeout 3

smtp_server 127.0.0.1

router_id LVS_DEVEL

}

vrrp_script check_run { #声明vrrp_script 的函数check_run

script "/root/mysql.sh"

interval 5

}

vrrp_sync_group VG1 {

group {

VI_1

}

}

vrrp_instance VI_1 {

state MASTER #指定主服务器节点为主节点，备用节点上设置为BACKUP即可

interface eth0 #指定虚拟IP的网络接口

virtual_router_id 51 #VRRP组名，两个节点的设置必须一样，以指明各个节点属于同一VRRP组

priority 100 #主节点的优先级,数字越，优先级越高。（1-254之间），备用节点必须比主节点优先级低。

advert_int 1 #组播信息发送间隔，两个节点设置必须一样

nopreempt

authentication { #设置验证信息，两个节点必须一致

auth_type PASS

auth_pass 1111

}

track_script { #调用函数代码块

check_run

}

virtual_ipaddress { #虚拟IP

192.168.1.30

}

}

MYSQL B服务器的keepalived配置如下：

! Configuration File for keepalived

global_defs {

notification_email {

[email protected]

}

notification_email_from [email protected]

smtp_connect_timeout 3

smtp_server 127.0.0.1

router_id LVS_DEVEL

}

vrrp_script check_run {

script "/root/mysql.sh"

interval 5

}

vrrp_sync_group VG1 {

group {

VI_1

}

}

vrrp_instance VI_1 {

state BACKUP

interface eth0

virtual_router_id 51

priority 90

advert_int 1

nopreempt

authentication {

auth_type PASS

auth_pass 1111

}

track_script {

check_run

}

virtual_ipaddress {

192.168.1.30

}

}

4、mysql状态检测脚本

在目录root下创建脚本mysql.sh：

#vim /root/mysql.sh

#!/bin/bash

MYSQL=/usr/local/mysql/bin/mysql

MYSQL_HOST=localhost

MYSQL_USER=root

MYSQL_PASSWORD=123456

CHECK_TIME=3

#mysql is working MYSQL_OK is 1 , mysql down MYSQL_OK is 0

MYSQL_OK=1

function check_mysql_helth (){

$MYSQL -h $MYSQL_HOST -u $MYSQL_USER -p${MYSQL_PASSWORD} -e "show status;" &>/dev/null

if [ $? = 0 ] ;then

MYSQL_OK=1

else

MYSQL_OK=0

fi

return $MYSQL_OK

}

while [ $CHECK_TIME -ne 0 ]

do

let "CHECK_TIME -= 1"

check_mysql_helth

if [ $MYSQL_OK = 1 ] ; then

CHECK_TIME=0

exit 0

fi

if [ $MYSQL_OK -eq 0 ] && [ $CHECK_TIME -eq 0 ]

then

pkill keepalived

exit 1

fi

sleep 1

done

5、两台服务器同时启动mysql和keepalived

#/etc/init.d/mysqld start

#/etc/init.d/keepalived start

6、查看vrrp通读记录，进行测试

[root@master1 ~]# tcpdump vrrp

tcpdump: verbose output suppressed, use -v or -vv for full protocol decode

listening on eth0, link-type EN10MB (Ethernet), capture size 65535 bytes

12:04:10.537618 IP master1 > vrrp.mcast.net: VRRPv2, Advertisement, vrid 51, prio 100, authtype simple, intvl 1s, length 20

12:04:11.540364 IP master1 > vrrp.mcast.net: VRRPv2, Advertisement, vrid 51, prio 100, authtype simple, intvl 1s, length 20

[root@master1 ~]# ip a

2: eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP qlen 1000

link/ether 00:0c:29:51:6e:1f brd ff:ff:ff:ff:ff:ff

inet 192.168.1.28/24 brd 192.168.1.255 scope global eth0

inet 192.168.1.30/32 scope global eth0

inet6 fe80::20c:29ff:fe51:6e1f/64 scope link

valid_lft forever preferred_lft forever

[root@master2 ~]# tcpdump vrrp

tcpdump: verbose output suppressed, use -v or -vv for full protocol decode

listening on eth0, link-type EN10MB (Ethernet), capture size 65535 bytes

15:15:02.529859 IP master1 > vrrp.mcast.net: VRRPv2, Advertisement, vrid 51, prio 100, authtype simple, intvl 1s, length 20

15:15:03.531873 IP master1 > vrrp.mcast.net: VRRPv2, Advertisement, vrid 51, prio 100, authtype simple, intvl 1s, length 20

[root@master2 ~]# ip a

2: eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP qlen 1000

link/ether 00:0c:29:87:90:e8 brd ff:ff:ff:ff:ff:ff

inet 192.168.1.29/24 brd 192.168.1.255 scope global eth0

inet6 fe80::20c:29ff:fe87:90e8/64 scope link

valid_lft forever preferred_lft forever

此时显示是master A服务器在提供服务。

关闭master A服务器上的mysql

[root@master1 ~]# /etc/init.d/mysqld stop

Shutting down MySQL. SUCCESS!

[root@master1 ~]# tcpdump vrrp

tcpdump: verbose output suppressed, use -v or -vv for full protocol decode

listening on eth0, link-type EN10MB (Ethernet), capture size 65535 bytes

14:03:00.245737 IP master2 > vrrp.mcast.net: VRRPv2, Advertisement, vrid 51, prio 90, authtype simple, intvl 1s, length 20

14:03:01.246680 IP master2 > vrrp.mcast.net: VRRPv2, Advertisement, vrid 51, prio 90, authtype simple, intvl 1s, length 20

[root@master1 ~]# ip a

2: eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP qlen 1000

link/ether 00:0c:29:51:6e:1f brd ff:ff:ff:ff:ff:ff

inet 192.168.1.28/24 brd 192.168.1.255 scope global eth0

inet6 fe80::20c:29ff:fe51:6e1f/64 scope link

valid_lft forever preferred_lft forever

[root@master2 ~]# tcpdump vrrp

tcpdump: verbose output suppressed, use -v or -vv for full protocol decode

listening on eth0, link-type EN10MB (Ethernet), capture size 65535 bytes

14:03:09.331826 IP master2 > vrrp.mcast.net: VRRPv2, Advertisement, vrid 51, prio 90, authtype simple, intvl 1s, length 20

14:03:10.333790 IP master2 > vrrp.mcast.net: VRRPv2, Advertisement, vrid 51, prio 90, authtype simple, intvl 1s, length 20

[root@master2 ~]# ip a

2: eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP qlen 1000

link/ether 00:0c:29:87:90:e8 brd ff:ff:ff:ff:ff:ff

inet 192.168.1.29/24 brd 192.168.1.255 scope global eth0

inet 192.168.1.30/32 scope global eth0

inet6 fe80::20c:29ff:fe87:90e8/64 scope link

valid_lft forever preferred_lft forever

然后由keepalived配置文件可以知道，mysql关闭的话，将会执行mysql.sh这一脚本。这个脚本在执行的时候，会判断mysql的状态，如果mysql关闭了，将会关闭keepalived进程。

还有一方式测试就是分别在两台服务器上建立远程连接用户，建立远程的用户时可以建立不同用户，或不同密码。

此方案还有一个缺点是当mysql服务器恢复正常时，需要手动启动keepalived服务，在网上有解决办法，不过我没成功。

下面两篇博客有兴趣可以参考下

http://blog.csdn.net/ssdbbg/article/details/8205509

http://bbs.chinaunix.net/thread-1824528-1-1.html