2.1.5、MySQL Keepalived 故障转移

3、在主库和备库上面安装keepalived

安装方式参照：http://www.cnblogs.com/galengao/p/5764163.html

可以选择安装最新版本

安装依赖包
yum install popt-static kernel-devel make gcc openssl-devel lftp libnl* popt*

安装keepalived
wget http://www.keepalived.org/software/keepalived-1.2.4.tar.gz
tar zxvf keepalived-1.2.4.tar.gz
cd keepalived-1.2.4
./configure –prefix=/usr/local/keepalived
make
make install

将keepalived做成启动服务，方便管理
cp /usr/local/keepalived/etc/rc.d/init.d/keepalived /etc/init.d/
cp /usr/local/keepalived/etc/sysconfig/keepalived /etc/sysconfig/
mkdir /etc/keepalived/
cp /usr/local/keepalived/etc/keepalived/keepalived.conf /etc/keepalived/
cp /usr/local/keepalived/sbin/keepalived /usr/sbin/

service keepalived start

MySQL架构为master-slave（主从），master故障自动切换到slave上。当然也可以设置为双master，但这里有个弊端：就是当主的压力很大时，从上延时很大，比如落后2000秒，此时主挂了，从接管（VIP漂移到从），用户刚才发表的文章，此时因为同步延时大，还没复制过来，于是用户又发表了一篇文章，当原来的master修好后，因从的IO和SQL线程还在开启状态，还会继续同步刚才没有同步复制完的数据，这时有可能把用户新发表的文章更改掉，造成用户数据丢失。

考虑到这种情况，我这里还是用的master-slave（主从）架构。

keepalive 安装很简单，这里不再啰嗦。主要看下配置文件和脚本：

# more /etc/keepalived/keepalived.conf  

global_defs {

  router_id KeepAlive_Mysql

}  

vrrp_script check_run {

script "/root/sh/mysql_check.sh"

interval 300 

}

vrrp_sync_group VG1 {

group {

VI_1

}

}

vrrp_instance VI_1 {

   state BACKUP

   interface eth0  

   virtual_router_id 51

   priority 100  

   advert_int 1

   nopreempt

   authentication {

       auth_type PASS

       auth_pass 1111

   }

   track_script {

   check_run

   }

   notify_master /root/sh/master.sh

   notify_backup /root/sh/backup.sh

   notify_stop /root/sh/stop.sh

   virtual_ipaddress {

       192.168.8.150

   }

}

notify_master | # 状态改变为MASTER后执行的脚本
notify_backup | # 状态改变为BACKUP后执行的脚本
notify_fault | # 状态改变为FAULT后执行的脚本
notify_stop | # VRRP停止后后执行的脚本
notify | # (1)任意状态改变后执行的脚本

下面解释下这4个脚本的用法：

mysql_check.sh（健康检查脚本，当发现mysql连接不上，会把keepalive进程关闭，并切换。）

# more mysql_check.sh  

#!/bin/bash

. /root/.bash_profile

count=1

while true

do

mysql -e "show status;" > /dev/null 2>&1

i=$?

ps aux | grep mysqld | grep -v grep > /dev/null 2>&1

j=$?

if [ $i = 0 ] && [ $j = 0 ]

then

  exit 0

else

  if [ $i = 1 ] && [ $j = 0 ]

  then

      exit 0

  else

       if [ $count -gt 5 ]

       then

             break

       fi

  let count++

  continue

  fi

fi

done

/etc/init.d/keepalived stop

master.sh（状态改变为MASTER后执行的脚本） （首先判断同步复制是否执行完毕，如果未执行完毕，等1分钟后，不论是否执行完毕，都跳过，并停止同步复制进程。） （其次，更改前端程序连接的业务账号admin的权限和密码，并记录当前切换以后的日志和POS点。）

# more master.sh

#!/bin/bash

. /root/.bash_profile

Master_Log_File=$(mysql -e "show slave statusG" | grep -w Master_Log_File | awk -F": " '{print $2}')

Relay_Master_Log_File=$(mysql -e "show slave statusG" | grep -w Relay_Master_Log_File | awk -F": " '{print $2}')

Read_Master_Log_Pos=$(mysql -e "show slave statusG" | grep -w Read_Master_Log_Pos | awk -F": " '{print $2}')

Exec_Master_Log_Pos=$(mysql -e "show slave statusG" | grep -w Exec_Master_Log_Pos | awk -F": " '{print $2}')

i=1

while true

do

if [ $Master_Log_File = $Relay_Master_Log_File ] && [ $Read_Master_Log_Pos -eq $Exec_Master_Log_Pos ]

then

  echo "ok"

  break

else

  sleep 1

  if [ $i -gt 60 ]

  then

     break

  fi

  continue

  let i++

fi

done

mysql -e "stop slave;"

mysql -e "flush logs;GRANT ALL PRIVILEGES ON *.* TO 'admin'@'%' IDENTIFIED BY 'admin';flush privileges;"

mysql -e "show master status;" > /tmp/master_status_$(date "+%y%m%d-%H%M").txt

backup.sh（状态改变为BACKUP后执行的脚本）

# more backup.sh  

#!/bin/bash

. /root/.bash_profile

mysql -e "GRANT ALL PRIVILEGES ON *.* TO 'admin'@'%' IDENTIFIED BY '1q2w3e4r';flush privileges;"

stop.sh（keepalived停止后后执行的脚本） （首先把admin密码更改掉） （其次，设置参数，保证不丢失数据） （最后，查看是否还有写操作，不论是否执行完毕，1分钟后都退出。）

# more stop.sh  

#!/bin/bash

. /root/.bash_profile

mysql -e "GRANT ALL PRIVILEGES ON *.* TO 'admin'@'%' IDENTIFIED BY '1q2w3e4r';flush privileges;"

mysql -e "set global innodb_support_xa=1;"

mysql -e "set global sync_binlog=1;"

mysql -e "set global innodb_flush_log_at_trx_commit=1;"

M_File1=$(mysql -e "show master statusG" | awk -F': ' '/File/{print $2}')

M_Position1=$(mysql -e "show master statusG" | awk -F': ' '/Position/{print $2}')

sleep 1

M_File2=$(mysql -e "show master statusG" | awk -F': ' '/File/{print $2}')

M_Position2=$(mysql -e "show master statusG" | awk -F': ' '/Position/{print $2}')

i=1

while true

do

if [ $M_File1 = $M_File2 ] && [ $M_Position1 -eq $M_Position2 ]

then

  echo "ok"

  break

else

  sleep 1

  if [ $i -gt 60 ]

  then

     break

  fi

  continue

  let i++

fi

done