keepalived 的热备可以看文档：keepalived的配置使用
mysql 的主从 的文档讲解：mysql 主从复制
keepalived的双主，就是主从的一种， 大家看一眼就懂了，为了省力， 下面的双主配置我直接网上找了一篇，在下面，大家随便看下
keepalived的双子多从的整体结构 如下图：
1、配置两台Mysql主主同步
[root@master ~]# yum install mysql-server mysql -y
[root@master ~]# service mysqld start
[root@master ~]# mysqladmin -u root password 123.com
[root@master ~]# vi /etc/my.cnf #开启二进制日志，设置id
[mysqld]
server-id = 1 #backup这台设置2
log-bin = mysql-bin
binlog-ignore-db = mysql,information_schema #忽略写入binlog日志的库
auto-increment-increment = 2 #字段变化增量值
auto-increment-offset = 1 #初始字段ID为1
slave-skip-errors = all #忽略所有复制产生的错误
[root@master ~]# service mysqld restart
#先查看下log bin日志和pos值位置
master配置如下：
[root@ master ~]# mysql -u root -p123.com
mysql> GRANT REPLICATION SLAVE ON *.* TO 'replication'@'192.168.0.%' IDENTIFIED BY 'replication';
mysql> flush privileges;
mysql> change master to
-> master_host='192.168.0.203',
-> master_user='replication',
-> master_password='replication',
-> master_log_file='mysql-bin.000002',
-> master_log_pos=106; #对端状态显示的值
mysql> start slave; #启动同步
backup配置如下：
[root@backup ~]# mysql -u root -p123.com
-> master_host='192.168.0.202',
-> master_log_pos=106;
mysql> start slave;
#主主同步配置完毕，查看同步状态Slave_IO和Slave_SQL是YES说明主主同步成功。
在master插入数据测试下：
在backup查看是否同步成功：
可以看到已经成功同步过去，同样在backup插入到user表数据，一样同步过去，双主就做成功了。
2、配置keepalived实现热备
[root@backup ~]# yum install -y pcre-devel openssl-devel popt-devel #安装依赖包
[root@master ~]# wget http://www.keepalived.org/software/keepalived-1.2.7.tar.gz
[root@master ~]# tar zxvf keepalived-1.2.7.tar.gz
[root@master ~]# cd keepalived-1.2.7
[root@master ~]#./configure --prefix=/usr/local/keepalived
make && make install
#将keepalived配置成系统服务
[root@master ~]# cp /usr/local/keepalived/etc/rc.d/init.d/keepalived /etc/init.d/
[root@master ~]# cp /usr/local/keepalived/etc/sysconfig/keepalived /etc/sysconfig/
[root@master ~]# mkdir /etc/keepalived/
[root@master ~]# cp /usr/local/keepalived/etc/keepalived/keepalived.conf /etc/keepalived/
[root@master ~]# cp /usr/local/keepalived/sbin/keepalived /usr/sbin/
[root@master ~]# vi /etc/keepalived/keepalived.conf
! Configuration File forkeepalived
global_defs {
notification_email {
}
notification_email_from [email protected]
smtp_server 127.0.0.1
smtp_connect_timeout 30
router_id MYSQL_HA #标识，双主相同
vrrp_instance VI_1 {
state BACKUP #两台都设置BACKUP
interface eth0
virtual_router_id 51 #主备相同
priority 100 #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 {
192.168.0.204
}
virtual_server 192.168.0.204 3306 {
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 192.168.0.202 3306 { #检测本地mysql，backup也要写检测本地mysql
weight 3
notify_down /usr/local/keepalived/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
}
}
[root@master ~]# vi /usr/local/keepalived/mysql.sh
#!/bin/bash
pkill keepalived
[root@master ~]# chmod +x /usr/local/keepalived/mysql.sh
[root@master ~]# /etc/init.d/keepalived start
#backup服务器只修改priority为90、nopreempt不设置、real_server设置本地IP。
#授权两台Mysql服务器允许root远程登录，用于在其他服务器登陆测试！
mysql> grant all on *.* to'root'@'192.168.0.%' identified by '123.com';
mysql> flush privileges;
3、测试高可用性
1、通过Mysql客户端通过VIP连接，看是否连接成功。
2、停止master这台mysql服务，是否能正常切换过去，可通过ip addr命令来查看VIP在哪台服务器上。