MySQL 高可用性之 Keepalived 双主热备

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转载补充:

通常说的「双机热备」是指两台机器都在运行,但并不是两台机器都同时在提供服务。当提供服务的一台出现故障的时候,另外一台会马上自动接管并且提供服务,而且切换的时间非常短。

Keepalived的工作原理是VRRP(virtual Router Redundancy Protocol)虚拟路由冗余协议。在VRRP中有两组重要的概念:VRRP路由器和虚拟路由器,主控路由器和备份路由器。

VRRP路由器是指运行VRRP的路由器,是物理实体,虚拟路由器是指VRRP协议创建的,是逻辑概念。一组VRRP路由器协同工作,共同构成一台虚拟路由器。 Vrrp中存在着一种选举机制,用以选出提供服务的路由即主控路由,其他的则成了备份路由。当主控路由失效后,备份路由中会重新选举出一个主控路由,来继续工作,来保障不间断服务。

环境描述:

  • OS:CentOS6.5_X64
  • MASTER:192.168.0.202
  • BACKUP:192.168.0.203
  • VIP:192.168.0.204

1、配置两台Mysql主主同步

[root@masterr ~]# yum install mysql-server mysql -y
[root@masterr ~]# service mysqld start
[root@masterr ~]# mysqladmin -u root password 123.com
[root@masterr ~]# 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@masterr ~]# service mysqld restart

#先查看下log bin日志和pos值位置

wKiom1MJYSngwysqAADkFn9zcK8686.jpg

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
mysql> GRANT  REPLICATION SLAVE ON *.* TO 'replication'@'192.168.0.%' IDENTIFIED  BY 'replication';
mysql> flush  privileges;
mysql> change  master to
    ->  master_host='192.168.0.202',
    ->  master_user='replication',
    ->  master_password='replication',
    ->  master_log_file='mysql-bin.000002',
    ->  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。

wKioL1MJYQ7QfZfXAAGQt0H1o1c742.jpg

在master插入数据测试下:

wKiom1MJYUCC0nlQAAEk4ruZ3ys652.jpg

在backup查看是否同步成功:

wKioL1MJYXyyChXUAADPZraUk3Y684.jpg

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@masterr ~]# wget http://www.keepalived.org/software/keepalived-1.2.7.tar.gz
[root@masterr ~]# tar zxvf keepalived-1.2.7.tar.gz
[root@masterr ~]# cd keepalived-1.2.7
[root@masterr ~]#./configure --prefix=/usr/local/keepalived
make

#将keepalived配置成系统服务

[root@masterr ~]# cp /usr/local/keepalived/etc/rc.d/init.d/keepalived /etc/init.d/
[root@masterr ~]# cp /usr/local/keepalived/etc/sysconfig/keepalived /etc/sysconfig/
[root@masterr ~]# mkdir /etc/keepalived/
[root@masterr ~]# cp /usr/local/keepalived/etc/keepalived/keepalived.conf /etc/keepalived/
[root@masterr ~]# cp /usr/local/keepalived/sbin/keepalived /usr/sbin/
[root@masterr ~]# vi /etc/keepalived/keepalived.conf
! Configuration File forkeepalived
global_defs {
notification_email {
test@sina.com
 }
notification_email_from  admin@test.com
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@masterr ~]# vi /usr/local/keepalived/mysql.sh
#!/bin/bash
pkill keepalived
[root@masterr ~]# chmod +x /usr/local/keepalived/mysql.sh
[root@masterr ~]# /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;

三、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。

wKiom1MJYbCBORSGAAHChWpI93k009.jpg

3、可通过查看/var/log/messges日志,看出主备切换过程

4、master服务器故障恢复后,是否主动抢占资源,成为活动服务器。

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