Keepalived+MySQL（双主热备）

环境描述：

OS：RedHat 6.5_X64

MASTER_A：10.211.55.13

MASTER_B：10.211.55.14

VIP：10.211.55.201

授权用户(已经授权的root用户可以省略)

MASTER_A：

mysql> grant replication slave,file on *.* to 'repl1'@'10.211.55.14' identified
by '123456';
Query OK, 0 rows affected (0.00 sec)

mysql> flush privileges;
Query OK, 0 rows affected (0.00 sec)

MASTER_B：

mysql> grant replication slave,file on *.* to 'repl2'@'10.211.55.13' identified
by '123456';
Query OK, 0 rows affected (0.00 sec)

mysql> flush privileges;
Query OK, 0 rows affected (0.00 sec)

配置两台Mysql主主同步

停止MySQL服务

service mysqld stop

修改MASTER_A配置文件

[root@master ~]# vi /etc/my.cnf  #开启二进制日志，设置id
[mysqld]
user = mysql
log-bin=mysql-bin
server-id       = 1
binlog-do-db=test
binlog-ignore-db=mysql
replicate-do-db=test
replicate-ignore-db=mysql
log-slave-updates
slave-skip-errors=all
skip-name-resolve
sync_binlog=1
auto_increment_increment=2
auto_increment_offset=1

修改MASTER_B配置文件

user = mysql
log-bin=mysql-bin
server-id       = 2
binlog-do-db=test
binlog-ignore-db=mysql
replicate-do-db=test
replicate-ignore-db=mysql
log-slave-updates
slave-skip-errors=all
skip-name-resolve
sync_binlog=1
auto_increment_increment=2
auto_increment_offset=2

至于这些参数的说明具体看手册。
log-slave-updates非常重要，如果一个MASTER 挂掉的话，另外一个马上接管。
sync_binlog auto_increment_increment auto_increment_offset指的是服务器频繁的刷新日志。这个保证了在其中一台挂掉的话，日志刷新到另外一台。从而保证了数据的同步 。

启动MySQL服务

service mysqld start

进入MYSQL的SHELL

MASTER_A：

mysql> flush tables with read lock\G
Query OK, 0 rows affected (0.00 sec)

mysql> show master status\G
*************************** 1. row ***************************
File: mysql-bin.000007
Position: 528
Binlog_Do_DB: test
Binlog_Ignore_DB: mysql
1 row in set (0.00 sec)

MASTER_B：

mysql> flush tables with read lock;
Query OK, 0 rows affected (0.00 sec)

mysql> show master status\G
*************************** 1. row ***************************
File: mysql-bin.000004
Position: 595
Binlog_Do_DB: test
Binlog_Ignore_DB: mysql
1 row in set (0.00 sec)

然后备份数据，保持两个机器的数据一致。

在各自机器上执行CHANGE MASTER TO命令。

MASTER_A：

mysql> change master to
    -> master_host='10.211.55.14',
    -> master_user='repl2',
    -> master_password='123456',
    -> master_log_file='mysql-bin.000004',
    -> master_log_pos=595;
Query OK, 0 rows affected (0.01 sec)
mysql> start slave;
Query OK, 0 rows affected (0.00 sec)

MASTER_B：

mysql> change master to
    -> master_host='10.211.55.13',
    -> master_user='repl1',
    -> master_password='123456',
    -> master_log_file='mysql-bin.000007',
    -> master_log_pos=528;
Query OK, 0 rows affected (0.01 sec)
mysql> start slave;
Query OK, 0 rows affected (0.00 sec)

查看同步状态

mysql> show slave status\G;

Slave_IO 和Slave_SQL是YES说明主主同步成功

测试主主状态

自行测试 增删改 等操作

配置keepalive

创建停止keepalived脚本

mkdir touch /usr/local/keepalived/scripts/
touch /usr/local/keepalived/scripts/check_mysql.sh
vi /usr/local/keepalived/scripts/check_mysql.sh

添加以下内容

#!/bin/bash
service keepalived stop

添加执行权限

chmod a+x /usr/local/keepalived/scripts/check_mysql.sh

编辑MASTER_A的keepalived.conf配置文件内容如下：

! 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 MYSQL_HA
}

vrrp_instance VI_1 {
    state BACKUP           #两台都设置BACKUP
    interface eth0         #监听的网卡
    virtual_router_id 51   #主备相同
    priority 100           #优先级，MASTER_B设置90
    advert_int 1
    nopreempt              #不主动抢占资源，只在master这台优先级高的设置，backup不设置
    authentication {
        auth_type PASS
        auth_pass 1111
    }
    virtual_ipaddress {
        10.211.55.201
    }
}

virtual_server 10.211.55.201 13306 {
    delay_loop 2
    #lb_algo rr              #LVS算法，用不到，我们就关闭了
    #lb_kind DR              #LVS模式，如果不关闭，备用服务器不能通过VIP连接主MySQL
    persistence_timeout 50  #同一IP的连接60秒内被分配到同一台真实服务器
    protocol TCP
    real_server 10.211.55.13 13306 {   #检测本地mysql，backup也要写检测本地mysql
    weight 3
    notify_down /usr/local/keepalived/scripts/check_mysql.sh    #当mysq服down时，执行此脚本，杀死keepalived实现切换
    TCP_CHECK {
        connect_timeout 3        #连接超时
        nb_get_retry 3           #重试次数
        delay_before_retry 3     #重试间隔时间
    }
}

编辑MASTER_B的keepalived.conf配置文件内容如下：

! 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 MYSQL_HA
}

vrrp_instance VI_1 {
    state BACKUP           #两台都设置BACKUP
    interface eth0         #监听的网卡
    virtual_router_id 51   #主备相同
    priority 90           #优先级，backup设置90
    advert_int 1
    #nopreempt              #不主动抢占资源，只在master这台优先级高的设置，backup不设置
    authentication {
        auth_type PASS
        auth_pass 1111
    }
    virtual_ipaddress {
        10.211.55.201
    }
}

virtual_server 10.211.55.201 13306 {
    delay_loop 2
    #lb_algo rr              #LVS算法，用不到，我们就关闭了
    #lb_kind DR              #LVS模式，如果不关闭，备用服务器不能通过VIP连接主MySQL
    persistence_timeout 50  #同一IP的连接60秒内被分配到同一台真实服务器
    protocol TCP
    real_server 10.211.55.14 13306 {   #检测本地mysql，backup也要写检测本地mysql
    weight 3
    notify_down /usr/local/keepalived/scripts/check_mysql.sh    #当mysq服down时，执行此脚本，杀死keepalived实现切换
    TCP_CHECK {
        connect_timeout 3        #连接超时
        nb_get_retry 3           #重试次数
        delay_before_retry 3     #重试间隔时间
    }
}

测试

配置完成后就可以运行看下效果了,分别在主从服务器上启动mysql和keepalived

service mysqld start
service keepalived start

启动之后通过 ip a 命令查看主服务器的网络信息，可以看到在eth0网卡下生成了10.211.55.201这个虚拟ip，并可通过这个ip访问到MySQL

参考资料：
http://lizhenliang.blog.51cto.com/7876557/1362313
http://www.jb51.net/article/38657.htm