使用keepalived搭建mysql主从备份、切换

原创

liuping0906 2013-09-12 15:11:59 ©著作权

文章标签 mysql keepalived 主从切换 master/master 文章分类 MySQL 数据库

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mysql master/slave结构最大的缺点：当master宕机时不能切换到slave，这样就影响了业务的运行。为了弥补这个缺陷，我采用了keepalived+master/master结构。如图：

关于mysql的配置请参考：http://liuping0906.blog.51cto.com/2516248/879877

安装keepalived

tar zxf keepalived-1.2.8.tar.gz
cd keepalived-1.2.8
./configure --prefix=/opt/app/keepalived-1.2.8
make
make install

在192.168.110.128上配置文件keepalived.conf

! Configuration File for keepalived
global_defs {
   router_id MYSQL-HA
}
vrrp_instance keepalive_mysql {
    state MASTER
    interface eth0
    virtual_router_id 51
    priority 100
    advert_int 1
    preempt
    authentication {
        auth_type PASS
        auth_pass 1111
    }
    virtual_ipaddress {
        192.168.110.8/24
    }
}

在192.168.110.137上配置文件keepalived.conf

! Configuration File for keepalived
global_defs {
    router_id MYSQL-HA
}
vrrp_instance keepalive_mysql {
    state BACKUP
    interface eth0
    virtual_router_id 51
    priority 99
    advert_int 1
    nopreempt
    authentication {
        auth_type PASS
        auth_pass 1111
    }
    virtual_ipaddress {
        192.168.110.8/24
    }
}

说明：

配置上注意priority的值，192.168.110.128是master，优先级要高。

preempt表示抢占服务，当192.168.110.128恢复后，重新把服务抢过来。

keepalived默认网卡eth0和自身服务出现问题时才会切换。

通过编写脚本来监控mysql的状态进而控制keeepalived服务

#!/bin/bash
MYSQL="/usr/bin/mysql"
MYSQL_HOST=127.0.0.1
MYSQL_USER=admin
MYSQL_PASSWORD=admin
LOG_FILE="/opt/app/keepalived/check_mysql.log"
MYSQL_OK=1 # mysql is working MYSQL_OK is 1 , mysql down MYSQL_OK is 0
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 :
do
  CHECK_TIME=3
  while [ $CHECK_TIME -ne 0 ]
  do
    let "CHECK_TIME -= 1"
    check_mysql_helth
    [ $MYSQL_OK == 1 ] && break
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                 
    if [ $MYSQL_OK -eq 0 ] && [ $CHECK_TIME -eq 0 ]; then
      pkill keepalived
      echo `date --date=today +"%Y-%M-%d %H:%m:%S"` - [INFO] - mysql invaild. keepalived stop. >> $LOG_FILE
    fi
  done
done

说明：

通过监控mysql服务状态来控制keepalived服务，这里mysql停掉则kill掉keepalived。

分别在两台机器上执行下面命令

shell>/opt/app/keepalived/sbin/keepalived -f \  /opt/app/keepalived/etc/keepalived/keepalived.conf -D
shell>nohup sh /opt/app/keepalived/bin/check_mysql.sh &

把第二条命令写入/etc/rc.local。

测试：

> ip addr