Mysql+Keepalived双主热备高可用操作记录

我们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。MySQL双主复制,即互为Master-Slave(只有一个Master提供写操作),可以实现数据库服务器的热备,但是一个Master宕机后不能实现动态切换。使用Keepalived,可以通过虚拟IP,实现双主对外的统一接口以及自动检查、失败切换机制,从而实现MySQL数据库的高可用方案。之前梳理了Mysql主从/主主同步,下面说下Mysql+keeoalived双主热备高可用方案的实施。

Keepalived看名字就知道,保持存活,在网络里面就是保持在线了,也就是所谓的高可用或热备,用来防止单点故障(单点故障是指一旦某一点出现故障就会导
整个系统架构的不可用)的发生,那说到keepalived不得不说的一个协议不是VRRP协议,可以说这个协议就是keepalived实现的基础。
1)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。
2)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。

过多内容在这里就不做详细介绍了,下面详细记录下Mysql+Keepalived双主热备的高可用方案的操作记录

1)先实施Master->Slave的主主同步。主主是数据双向同步,主从是数据单向同步。一般情况下,主库宕机后,需要手动将连接切换到从库上。(但是用keepalived就可以自动切换)
2)再结合Keepalived的使用,通过VIP实现Mysql双主对外连接的统一接口。即客户端通过Vip连接数据库;当其中一台宕机后,VIP会漂移到另一台上,这个过程对于客户端的数据连接来说几乎无感觉,从而实现高可用。
环境描述:
mysql的安装可以参考:http://www.cnblogs.com/kevingrace/p/6109679.html
Centos6.8版本
Master1:182.148.15.238        安装mysql和keepalived
Master2: 182.148.15.237        安装mysql和keepalived
VIP:182.148.15.236
   
要实现主主同步,可以先实现主从同步,即master1->master2的主从同步,然后master2->master1的主从同步.
这样,双方就完成了主主同步。

注意下面几点:
1)要保证同步服务期间之间的网络联通。即能相互ping通,能使用对方授权信息连接到对方数据库(防火墙开放3306端口)。
2)关闭selinux。
3)同步前,双方数据库中需要同步的数据要保持一致。这样,同步环境实现后,再次更新的数据就会如期同步了。

可能出现的问题

报错:
Last_IO_Error: Fatal error: The slave I/O thread stops because master and slave have equal MySQL server ids; these ids must be different for replication to work (or the --replicate-same-server-id option must be used on slave but this does not always make sense; please check the manual before using it).
 
解决办法:
删除mysql数据目录下的auto.cnf文件,重启mysql服务即可!

另:Keepalived必须使用root账号启动!!

一、Mysql主主同步环境部署

---------------master1服务器操作记录---------------
在my.cnf文件的[mysqld]配置区域添加下面内容:
[root@master1 ~]# vim /usr/local/mysql/my.cnf
server-id = 1          
log-bin = mysql-bin      
sync_binlog = 1
binlog_checksum = none
binlog_format = mixed
auto-increment-increment = 2      
auto-increment-offset = 1     
slave-skip-errors = all       
 
[root@master1 ~]# /etc/init.d/mysql restart
Shutting down MySQL. SUCCESS!
Starting MySQL.. SUCCESS!
 
数据同步授权(iptables防火墙开启3306端口)这样I/O线程就可以以这个用户的身份连接到主服务器,并且读取它的二进制日志。
mysql> grant replication slave,replication client on *.* to wang@'182.148.15.%' identified by "wang@123";
Query OK, 0 rows affected (0.00 sec)
 
mysql> flush privileges;
Query OK, 0 rows affected (0.00 sec)
 
最好将库锁住,仅仅允许读,以保证数据一致性;待主主同步环境部署后再解锁;
锁住后,就不能往表里写数据,但是重启mysql服务后就会自动解锁!
mysql> flush tables with read lock;  //注意该参数设置后,如果自己同步对方数据,同步前一定要记得先解锁!
Query OK, 0 rows affected (0.00 sec)
 
查看下log bin日志和pos值位置
mysql> show master status;
+------------------+----------+--------------+--------------------------+-------------------+
| File             | Position | Binlog_Do_DB | Binlog_Ignore_DB         | Executed_Gtid_Set |
+------------------+----------+--------------+--------------------------+-------------------+
| mysql-bin.000004 |      430 |              | mysql,information_schema |                   |
+------------------+----------+--------------+--------------------------+-------------------+
1 row in set (0.00 sec)
 
---------------master2服务器操作记录---------------
在my.cnf文件的[mysqld]配置区域添加下面内容:
[root@master2 ~]# vim /usr/local/mysql/my.cnf
server-id = 2         
log-bin = mysql-bin     
sync_binlog = 1
binlog_checksum = none
binlog_format = mixed
auto-increment-increment = 2      
auto-increment-offset = 2     
slave-skip-errors = all 
 
[root@master2 ~]# /etc/init.d/mysql restart
Shutting down MySQL.. SUCCESS!
Starting MySQL.. SUCCESS!
 
mysql> grant replication slave,replication client on *.* to wang@'182.148.15.%' identified by "wang@123";
Query OK, 0 rows affected (0.00 sec)
 
mysql> flush privileges;
Query OK, 0 rows affected (0.00 sec)
 
mysql> flush tables with read lock;
Query OK, 0 rows affected (0.00 sec)
 
mysql> show master status;
+------------------+----------+--------------+--------------------------+-------------------+
| File             | Position | Binlog_Do_DB | Binlog_Ignore_DB         | Executed_Gtid_Set |
+------------------+----------+--------------+--------------------------+-------------------+
| mysql-bin.000003 |      430 |              | mysql,information_schema |                   |
+------------------+----------+--------------+--------------------------+-------------------+
1 row in set (0.00 sec)
 
---------------master1服务器做同步操作---------------
mysql> unlock tables;     //先解锁,将对方数据同步到自己的数据库中
mysql> slave stop;
mysql> change  master to master_host='182.148.15.237',master_user='wang',master_password='wang@123',master_log_file='mysql-bin.000003',master_log_pos=430;          
Query OK, 0 rows affected, 2 warnings (0.01 sec)
 
mysql> start slave;
Query OK, 0 rows affected (0.01 sec)
 
查看同步状态,如下出现两个“Yes”,表明同步成功!
mysql> show slave status \G;
*************************** 1. row ***************************
               Slave_IO_State: Waiting for master to send event
                  Master_Host: 182.148.15.237
                  Master_User: wang
                  Master_Port: 3306
                Connect_Retry: 60
              Master_Log_File: mysql-bin.000003
          Read_Master_Log_Pos: 430
               Relay_Log_File: mysql-relay-bin.000002
                Relay_Log_Pos: 279
        Relay_Master_Log_File: mysql-bin.000003
             Slave_IO_Running: Yes
            Slave_SQL_Running: Yes
        .........................
        Seconds_Behind_Master: 0
        .........................

这样,master1就和master2实现了主从同步,即master1同步master2的数据。
 
---------------master2服务器做同步操作---------------
mysql> unlock tables;     //先解锁,将对方数据同步到自己的数据库中
mysql> slave stop;
mysql> change  master to master_host='182.148.15.238',master_user='wang',master_password='wang@123',master_log_file='mysql-bin.000004',master_log_pos=430;   
Query OK, 0 rows affected, 2 warnings (0.06 sec)
 
mysql> start slave;
Query OK, 0 rows affected (0.01 sec)
 
mysql> show slave status \G;
*************************** 1. row ***************************
               Slave_IO_State: Waiting for master to send event
                  Master_Host: 182.148.15.238
                  Master_User: wang
                  Master_Port: 3306
                Connect_Retry: 60
              Master_Log_File: mysql-bin.000004
          Read_Master_Log_Pos: 430
               Relay_Log_File: mysql-relay-bin.000002
                Relay_Log_Pos: 279
        Relay_Master_Log_File: mysql-bin.000004
             Slave_IO_Running: Yes
            Slave_SQL_Running: Yes
        ........................
        Seconds_Behind_Master: 0
        ........................
 
这样,master2就和master1实现了主从同步,即master2也同步master1的数据。
 
以上表明双方已经实现了mysql主主同步。
当运行一段时间后,要是发现同步有问题,比如只能单向同步,双向同步失效。可以重新执行下上面的change master同步操作,只不过这样同步后,只能同步在此之后的更新数据。下面开始进行数据验证:
 
-----------------主主同步效果验证--------------------- 
1)在master1数据库上写入新数据
mysql> unlock tables;
Query OK, 0 rows affected (0.00 sec)
 
mysql> create database huanqiu;
Query OK, 1 row affected (0.01 sec)
 
mysql> use huanqiu;
Database changed
 
mysql> create table if not exists haha (
    -> id int(10) PRIMARY KEY AUTO_INCREMENT,
    -> name varchar(50) NOT NULL);
Query OK, 0 rows affected (0.04 sec)
 
mysql> insert into haha values(1,"王士博");
Query OK, 1 row affected (0.00 sec)
 
mysql> insert into haha values(2,"郭慧慧");
Query OK, 1 row affected (0.00 sec)
 
mysql> select * from haha;
+----+-----------+
| id | name      |
+----+-----------+
|  1 | 王士博    |
|  2 | 郭慧慧    |
+----+-----------+
2 rows in set (0.00 sec)
 
然后在master2数据库上查看,发现数据已经同步过来了!
mysql> show databases;
+--------------------+
| Database           |
+--------------------+
| information_schema |
| huanqiu            |
| mysql              |
| performance_schema |
| test               |
+--------------------+
5 rows in set (0.00 sec)
 
mysql> use huanqiu;
Reading table information for completion of table and column names
You can turn off this feature to get a quicker startup with -A
 
Database changed
mysql> show tables;
+-------------------+
| Tables_in_huanqiu |
+-------------------+
| haha              |
+-------------------+
1 row in set (0.00 sec)
 
mysql> select * from haha;
+----+-----------+
| id | name      |
+----+-----------+
|  1 | 王士博    |
|  2 | 郭慧慧    |
+----+-----------+
2 rows in set (0.00 sec)
 
2)在master2数据库上写入新数据
mysql> create database hehe;
Query OK, 1 row affected (0.00 sec)
 
mysql> insert into huanqiu.haha values(3,"周正"),(4,"李敏");
Query OK, 2 rows affected (0.00 sec)
Records: 2  Duplicates: 0  Warnings: 0
 
然后在master1数据库上查看,发现数据也已经同步过来了!
mysql> show databases;
+--------------------+
| Database           |
+--------------------+
| information_schema |
| hehe               |
| huanqiu            |
| mysql              |
| performance_schema |
| test               |
+--------------------+
6 rows in set (0.00 sec)
 
mysql> select * from huanqiu.haha;
+----+-----------+
| id | name      |
+----+-----------+
|  1 | 王士博    |
|  2 | 郭慧慧    |
|  3 | 周正      |
|  4 | 李敏      |
+----+-----------+
4 rows in set (0.00 sec)
 
至此,Mysql主主同步环境已经实现。

二、配置Mysql+Keepalived故障转移的高可用环境

1)安装keepalived并将其配置成系统服务。master1和master2两台机器上同样进行如下操作:
[root@master1 ~]# yum install -y openssl-devel
[root@master1 ~]# cd /usr/local/src/
[root@master1 src]# wget http://www.keepalived.org/software/keepalived-1.3.5.tar.gz
[root@master1 src]# tar -zvxf keepalived-1.3.5.tar.gz
[root@master1 src]# cd keepalived-1.3.5
[root@master1 keepalived-1.3.5]# ./configure --prefix=/usr/local/keepalived
[root@master1 keepalived-1.3.5]# make && make install
    
[root@master1 keepalived-1.3.5]# cp /usr/local/src/keepalived-1.3.5/keepalived/etc/init.d/keepalived /etc/rc.d/init.d/
[root@master1 keepalived-1.3.5]# cp /usr/local/keepalived/etc/sysconfig/keepalived /etc/sysconfig/
[root@master1 keepalived-1.3.5]# mkdir /etc/keepalived/
[root@master1 keepalived-1.3.5]# cp /usr/local/keepalived/etc/keepalived/keepalived.conf /etc/keepalived/
[root@master1 keepalived-1.3.5]# cp /usr/local/keepalived/sbin/keepalived /usr/sbin/
[root@master1 keepalived-1.3.5]# echo "/etc/init.d/keepalived start" >> /etc/rc.local
    
2)master1机器上的keepalived.conf配置。(下面配置中没有使用lvs的负载均衡功能,所以不需要配置虚拟服务器virtual server)
[root@master1 ~]# cp /etc/keepalived/keepalived.conf /etc/keepalived/keepalived.conf.bak
[root@master1 ~]# vim /etc/keepalived/keepalived.conf       #清空默认内容,直接采用下面配置:
! Configuration File for keepalived
      
global_defs {
notification_email { 
ops@wangshibo.cn
tech@wangshibo.cn
}
      
notification_email_from ops@wangshibo.cn
smtp_server 127.0.0.1  
smtp_connect_timeout 30
router_id MASTER-HA
}
      
vrrp_script chk_mysql_port {     #检测mysql服务是否在运行。有很多方式,比如进程,用脚本检测等等
    script "/opt/chk_mysql.sh"   #这里通过脚本监测
    interval 2                   #脚本执行间隔,每2s检测一次
    weight -5                    #脚本结果导致的优先级变更,检测失败(脚本返回非0)则优先级 -5
    fall 2                    #检测连续2次失败才算确定是真失败。会用weight减少优先级(1-255之间)
    rise 1                    #检测1次成功就算成功。但不修改优先级
}
      
vrrp_instance VI_1 {
    state MASTER     
    interface eth0      #指定虚拟ip的网卡接口
    mcast_src_ip 182.148.15.238
    virtual_router_id 51    #路由器标识,MASTER和BACKUP必须是一致的
    priority 101            #定义优先级,数字越大,优先级越高,在同一个vrrp_instance下,MASTER的优先级必须大于BACKUP的优先级。这样MASTER故障恢复后,就可以将VIP资源再次抢回来  
    advert_int 1          
    authentication {    
        auth_type PASS  
        auth_pass 1111      
    }
    virtual_ipaddress {     
        182.148.15.236
    }
     
track_script {                
   chk_mysql_port              
}
}
    
编写切换脚本。KeepAlived做心跳检测,如果Master的MySQL服务挂了(3306端口挂了),那么它就会选择自杀。Slave的KeepAlived通过心跳检测发现这个情况,就会将VIP的请求接管
[root@master1 ~]# vim /opt/chk_mysql.sh
#!/bin/bash
counter=$(netstat -na|grep "LISTEN"|grep "3306"|wc -l)
if [ "${counter}" -eq 0 ]; then
    /etc/init.d/keepalived stop
fi

[root@master1 ~]# chmod 755 /opt/chk_mysql.sh
    
启动keepalived服务
[root@master1 ~]# /etc/init.d/keepalived start
正在启动 keepalived:                                      [确定]
    
    
4)master2机器上的keepalived配置。master2机器上的keepalived.conf文件只修改priority为90、nopreempt不设置、real_server设置本地IP。
[root@master2 ~]# cp /etc/keepalived/keepalived.conf /etc/keepalived/keepalived.conf.bak
[root@master2 ~]# >/etc/keepalived/keepalived.conf
[root@master2 ~]# vim /etc/keepalived/keepalived.conf
! Configuration File for keepalived
      
global_defs {
notification_email { 
ops@wangshibo.cn
tech@wangshibo.cn
}
      
notification_email_from ops@wangshibo.cn
smtp_server 127.0.0.1  
smtp_connect_timeout 30
router_id MASTER-HA
}
      
vrrp_script chk_mysql_port { 
    script "/opt/chk_mysql.sh"
    interval 2             
    weight -5                  
    fall 2                  
    rise 1                
}
      
vrrp_instance VI_1 {
    state BACKUP
    interface eth0     
    mcast_src_ip 182.148.15.237
    virtual_router_id 51     
    priority 99           
    advert_int 1          
    authentication {    
        auth_type PASS  
        auth_pass 1111      
    }
    virtual_ipaddress {     
        182.148.15.236
    }
     
track_script {                
   chk_mysql_port              
}
}
    
    
[root@master2 ~]# cat /opt/chk_mysql.sh
#!/bin/bash
counter=$(netstat -na|grep "LISTEN"|grep "3306"|wc -l)
if [ "${counter}" -eq 0 ]; then
    /etc/init.d/keepalived stop
fi

[root@master2 ~]# chmod 755 /opt/chk_mysql.sh
    
[root@master2 ~]# /etc/init.d/keepalived start
正在启动 keepalived:                                      [确定]
    
    
5)master1和master2两台服务器都要授权允许root用户远程登录,用于在客户端登陆测试!
mysql> grant all on *.* to root@'%' identified by "1234567";
Query OK, 0 rows affected (0.00 sec)
    
mysql> flush privileges;
Query OK, 0 rows affected (0.01 sec)
  
6)在master1和master2两台机器上设置iptables防火墙规则,如下:
[root@master1 ~]# cat /etc/sysconfig/iptables
........
-A INPUT -s 182.148.15.0/24 -d 224.0.0.18 -j ACCEPT       #允许组播地址通信
-A INPUT -s 182.148.15.0/24 -p vrrp -j ACCEPT             #允许VRRP(虚拟路由器冗余协)通信
-A INPUT -m state --state NEW -m tcp -p tcp --dport 3306 -j ACCEPT    #开放mysql的3306端口
  
[root@master1 ~]# /etc/init.d/iptables restart

三、Mysql+keepalived故障转移的高可用测试

1)通过Mysql客户端通过VIP连接,看是否连接成功。
比如,在远程一台测试机上连接,通过vip地址可以正常连接(下面的连接权限要是在服务端提前授权的)
[root@dev-new-test ~]# mysql -h182.148.15.236 -uroot -p123456
Welcome to the MySQL monitor.  Commands end with ; or \g.
Your MySQL connection id is 60
Server version: 5.6.35-log Source distribution

Copyright (c) 2000, 2013, Oracle and/or its affiliates. All rights reserved.

Oracle is a registered trademark of Oracle Corporation and/or its
affiliates. Other names may be trademarks of their respective
owners.

Type 'help;' or '\h' for help. Type '\c' to clear the current input statement.

mysql> select * from huanqiu.haha;
+----+-----------+
| id | name      |
+----+-----------+
|  1 | 王士博    |
|  2 | 郭慧慧    |
|  3 | 周正      |
|  4 | 李敏      |
+----+-----------+
4 rows in set (0.00 sec)


2)默认情况下,vip是在master1上的。使用"ip addr"命令查看vip切换情况  
[root@master1 ~]# ip addr
1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN 
    link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
    inet 127.0.0.1/8 scope host lo
    inet6 ::1/128 scope host 
       valid_lft forever preferred_lft forever
2: eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP qlen 1000
    link/ether 52:54:00:3c:25:42 brd ff:ff:ff:ff:ff:ff
    inet 182.148.15.238/27 brd 182.148.15.255 scope global eth0
    inet 182.148.15.236/32 scope global eth0                              //这个32位子网掩码的vip地址表示该资源目前还在master1机器上
    inet 182.148.15.236/27 brd 82.48.115.255 scope global secondary eth0:0
    inet6 fe80::5054:ff:fe3c:2542/64 scope link 
       valid_lft forever preferred_lft forever

停止master1机器上的mysql服务,根据配置中的脚本,mysql服务停了,keepalived也会停,从而vip资源将会切换到master2机器上。(mysql服务没有起来的时候,keepalived服务也无法顺利启动!)
[root@master1 ~]# /etc/init.d/mysql stop
Shutting down MySQL.. SUCCESS! 
[root@master1 ~]# ps -ef|grep mysql
root     25812 21588  0 17:30 pts/0    00:00:00 grep mysql
[root@master1 ~]# ps -ef|grep keepalived
root     25814 21588  0 17:30 pts/0    00:00:00 grep keepalived
[root@master1 ~]# ip addr                   
1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN 
    link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
    inet 127.0.0.1/8 scope host lo
    inet6 ::1/128 scope host 
       valid_lft forever preferred_lft forever
2: eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP qlen 1000
    link/ether 52:54:00:3c:25:42 brd ff:ff:ff:ff:ff:ff
    inet 182.148.15.238/27 brd 182.148.15.255 scope global eth0
    inet 182.148.15.236/27 brd 82.48.115.255 scope global secondary eth0:0
    inet6 fe80::5054:ff:fe3c:2542/64 scope link 
       valid_lft forever preferred_lft forever

如上结果,发现32位子网掩码的vip没有了,说明此时vip资源已不在master1机器上了
查看下master1的系统日志,如下,会发现vip资源已经切换走了
[root@master1 ~]# tail -f /var/log/messages 
Apr 15 17:17:43 localhost Keepalived_vrrp[23037]: Sending gratuitous ARP on eth0 for 182.148.15.236
Apr 15 17:17:48 localhost Keepalived_vrrp[23037]: Sending gratuitous ARP on eth0 for 182.148.15.236
Apr 15 17:17:48 localhost Keepalived_vrrp[23037]: VRRP_Instance(VI_1) Sending/queueing gratuitous ARPs on eth0 for 182.148.15.236
Apr 15 17:17:48 localhost Keepalived_vrrp[23037]: Sending gratuitous ARP on eth0 for 182.148.15.236
Apr 15 17:17:48 localhost Keepalived_vrrp[23037]: Sending gratuitous ARP on eth0 for 182.148.15.236
Apr 15 17:17:48 localhost Keepalived_vrrp[23037]: Sending gratuitous ARP on eth0 for 182.148.15.236
Apr 15 17:17:48 localhost Keepalived_vrrp[23037]: Sending gratuitous ARP on eth0 for 182.148.15.236
Apr 15 17:30:39 localhost Keepalived_healthcheckers[23036]: Stopped
Apr 15 17:30:39 localhost Keepalived_vrrp[23037]: VRRP_Instance(VI_1) sent 0 priority
Apr 15 17:30:39 localhost Keepalived_vrrp[23037]: VRRP_Instance(VI_1) removing protocol VIPs.

再到master2机器上,发现vip资源的确切换过来了
[root@master2 ~]# ip addr
1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN 
    link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
    inet 127.0.0.1/8 scope host lo
    inet6 ::1/128 scope host 
       valid_lft forever preferred_lft forever
2: eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP qlen 1000
    link/ether 52:54:00:95:1f:6d brd ff:ff:ff:ff:ff:ff
    inet 182.148.15.237/27 brd 182.148.15.255 scope global eth0
    inet 182.148.15.236/32 scope global eth0
    inet6 fe80::5054:ff:fe95:1f6d/64 scope link 
       valid_lft forever preferred_lft forever

查看master2的系统日志
[root@master2 ~]# tail -f /var/log/messages 
Apr 15 17:30:41 localhost Keepalived_vrrp[8731]: Sending gratuitous ARP on eth0 for 182.148.15.236
Apr 15 17:30:41 localhost Keepalived_vrrp[8731]: Sending gratuitous ARP on eth0 for 182.148.15.236
Apr 15 17:30:41 localhost Keepalived_vrrp[8731]: Sending gratuitous ARP on eth0 for 182.148.15.236
Apr 15 17:30:41 localhost Keepalived_vrrp[8731]: Sending gratuitous ARP on eth0 for 182.148.15.236
Apr 15 17:30:46 localhost Keepalived_vrrp[8731]: Sending gratuitous ARP on eth0 for 182.148.15.236
Apr 15 17:30:46 localhost Keepalived_vrrp[8731]: VRRP_Instance(VI_1) Sending/queueing gratuitous ARPs on eth0 for 182.148.15.236
Apr 15 17:30:46 localhost Keepalived_vrrp[8731]: Sending gratuitous ARP on eth0 for 182.148.15.236
Apr 15 17:30:46 localhost Keepalived_vrrp[8731]: Sending gratuitous ARP on eth0 for 182.148.15.236
Apr 15 17:30:46 localhost Keepalived_vrrp[8731]: Sending gratuitous ARP on eth0 for 182.148.15.236
Apr 15 17:30:46 localhost Keepalived_vrrp[8731]: Sending gratuitous ARP on eth0 for 182.148.15.236

3)再次启动master1的mysql和keepalived服务。(注意:如果restart重启mysql,那么还要启动下keepalived,因为mysql重启,根据脚本会造成keepalived关闭)
注意:一定要先启动mysql服务,然后再启动keepalived服务。如果先启动keepalived服务,按照上面的配置,mysql没有起来,就会自动关闭keepalived。
[root@master1 ~]# /etc/init.d/mysql start
Starting MySQL.. SUCCESS! 

[root@master1 ~]# /etc/init.d/keepalived start
正在启动 keepalived:                                      [确定]

启动这两个服务器后,稍微等过一会儿,注意观察会发现vip资源再次从master2机器上切换回来了。
[root@master1 ~]# ip addr
1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN 
    link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
    inet 127.0.0.1/8 scope host lo
    inet6 ::1/128 scope host 
       valid_lft forever preferred_lft forever
2: eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP qlen 1000
    link/ether 52:54:00:3c:25:42 brd ff:ff:ff:ff:ff:ff
    inet 182.148.15.238/27 brd 182.148.15.255 scope global eth0
    inet 182.148.15.236/32 scope global eth0
    inet 182.148.15.236/27 brd 82.48.115.255 scope global secondary eth0:0
    inet6 fe80::5054:ff:fe3c:2542/64 scope link 
       valid_lft forever preferred_lft forever

[root@master1 ~]# tail -f /var/log/messages 
Apr 15 17:40:41 localhost Keepalived_vrrp[27002]: Sending gratuitous ARP on eth0 for 182.148.15.236
Apr 15 17:40:41 localhost Keepalived_vrrp[27002]: Sending gratuitous ARP on eth0 for 182.148.15.236
Apr 15 17:40:41 localhost Keepalived_vrrp[27002]: Sending gratuitous ARP on eth0 for 182.148.15.236
Apr 15 17:40:41 localhost Keepalived_vrrp[27002]: Sending gratuitous ARP on eth0 for 182.148.15.236
Apr 15 17:40:46 localhost Keepalived_vrrp[27002]: Sending gratuitous ARP on eth0 for 182.148.15.236
Apr 15 17:40:46 localhost Keepalived_vrrp[27002]: VRRP_Instance(VI_1) Sending/queueing gratuitous ARPs on eth0 for 182.148.15.236
Apr 15 17:40:46 localhost Keepalived_vrrp[27002]: Sending gratuitous ARP on eth0 for 182.148.15.236
Apr 15 17:40:46 localhost Keepalived_vrrp[27002]: Sending gratuitous ARP on eth0 for 182.148.15.236
Apr 15 17:40:46 localhost Keepalived_vrrp[27002]: Sending gratuitous ARP on eth0 for 182.148.15.236
Apr 15 17:40:46 localhost Keepalived_vrrp[27002]: Sending gratuitous ARP on eth0 for 182.148.15.236

再看看master2机器,发现vip资源又被恢复后的master1抢过去了
[root@master2 ~]# ip addr
1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN 
    link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
    inet 127.0.0.1/8 scope host lo
    inet6 ::1/128 scope host 
       valid_lft forever preferred_lft forever
2: eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP qlen 1000
    link/ether 52:54:00:95:1f:6d brd ff:ff:ff:ff:ff:ff
    inet 182.148.15.237/27 brd 182.148.15.255 scope global eth0
    inet6 fe80::5054:ff:fe95:1f6d/64 scope link 
       valid_lft forever preferred_lft forever

[root@master2 ~]# tail -f /var/log/messages 
Apr 15 17:30:41 localhost Keepalived_vrrp[8731]: Sending gratuitous ARP on eth0 for 182.148.15.236
Apr 15 17:30:46 localhost Keepalived_vrrp[8731]: Sending gratuitous ARP on eth0 for 182.148.15.236
Apr 15 17:30:46 localhost Keepalived_vrrp[8731]: VRRP_Instance(VI_1) Sending/queueing gratuitous ARPs on eth0 for 182.148.15.236
Apr 15 17:30:46 localhost Keepalived_vrrp[8731]: Sending gratuitous ARP on eth0 for 182.148.15.236
Apr 15 17:30:46 localhost Keepalived_vrrp[8731]: Sending gratuitous ARP on eth0 for 182.148.15.236
Apr 15 17:30:46 localhost Keepalived_vrrp[8731]: Sending gratuitous ARP on eth0 for 182.148.15.236
Apr 15 17:30:46 localhost Keepalived_vrrp[8731]: Sending gratuitous ARP on eth0 for 182.148.15.236
Apr 15 17:40:41 localhost Keepalived_vrrp[8731]: VRRP_Instance(VI_1) Received advert with higher priority 101, ours 99
Apr 15 17:40:41 localhost Keepalived_vrrp[8731]: VRRP_Instance(VI_1) Entering BACKUP STATE
Apr 15 17:40:41 localhost Keepalived_vrrp[8731]: VRRP_Instance(VI_1) removing protocol VIPs.

4)同样,关闭master1机器的keepalived服务,vip资源会自动切换到master2机器上。当master1的keepalived服务恢复后,会将vip资源再次切回来。
[root@master1 ~]# /etc/init.d/keepalived stop
停止 keepalived:                                          [确定]
[root@master1 ~]# ip addr
1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN 
    link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
    inet 127.0.0.1/8 scope host lo
    inet6 ::1/128 scope host 
       valid_lft forever preferred_lft forever
2: eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP qlen 1000
    link/ether 52:54:00:3c:25:42 brd ff:ff:ff:ff:ff:ff
    inet 182.148.15.238/27 brd 182.148.15.255 scope global eth0
    inet 182.148.15.236/27 brd 82.48.115.255 scope global secondary eth0:0
    inet6 fe80::5054:ff:fe3c:2542/64 scope link 
       valid_lft forever preferred_lft forever

查看master2,发现vip切过来了
[root@master2 ~]# ip addr
1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN 
    link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
    inet 127.0.0.1/8 scope host lo
    inet6 ::1/128 scope host 
       valid_lft forever preferred_lft forever
2: eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP qlen 1000
    link/ether 52:54:00:95:1f:6d brd ff:ff:ff:ff:ff:ff
    inet 182.148.15.237/27 brd 182.148.15.255 scope global eth0
    inet 182.148.15.236/32 scope global eth0
    inet6 fe80::5054:ff:fe95:1f6d/64 scope link 
       valid_lft forever preferred_lft forever

再次恢复master1的keepalived服务,发现vip资源很快油切回来了。
[root@master1 ~]# /etc/init.d/keepalived start
正在启动 keepalived:                                      [确定]
[root@master1 ~]# ip addr
1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN 
    link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
    inet 127.0.0.1/8 scope host lo
    inet6 ::1/128 scope host 
       valid_lft forever preferred_lft forever
2: eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP qlen 1000
    link/ether 52:54:00:3c:25:42 brd ff:ff:ff:ff:ff:ff
    inet 182.148.15.238/27 brd 182.148.15.255 scope global eth0
    inet 182.148.15.236/32 scope global eth0
    inet 182.148.15.236/27 brd 82.48.115.255 scope global secondary eth0:0
    inet6 fe80::5054:ff:fe3c:2542/64 scope link 
       valid_lft forever preferred_lft forever

在此查看master2,发现vip资源被切走了
[root@master2 ~]# ip addr
1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN 
    link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
    inet 127.0.0.1/8 scope host lo
    inet6 ::1/128 scope host 
       valid_lft forever preferred_lft forever
2: eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP qlen 1000
    link/ether 52:54:00:95:1f:6d brd ff:ff:ff:ff:ff:ff
    inet 182.148.15.237/27 brd 182.148.15.255 scope global eth0
    inet6 fe80::5054:ff:fe95:1f6d/64 scope link 
       valid_lft forever preferred_lft forever

以上在vip资源切换过程中,对于客户端连接mysql(使用vip连接)来说几乎是没有任何影响的。

------------------------------------温馨提示(Keepalived的抢占和非抢占模式)---------------------------------------

keepalive是基于vrrp协议在linux主机上以守护进程方式,根据配置文件实现健康检查。
VRRP是一种选择协议,它可以把一个虚拟路由器的责任动态分配到局域网上的VRRP路由器中的一台。
控制虚拟路由器IP地址的VRRP路由器称为主路由器,它负责转发数据包到这些虚拟IP地址。
一旦主路由器不可用,这种选择过程就提供了动态的故障转移机制,这就允许虚拟路由器的IP地址可以作为终端主机的默认第一跳路由器。

keepalive通过组播,单播等方式(自定义),实现keepalive主备推选。工作模式分为抢占和非抢占(通过参数nopreempt来控制)。
1)抢占模式:
主服务正常工作时,虚拟IP会在主上,备不提供服务,当主服务优先级低于备的时候,备会自动抢占虚拟IP,这时,主不提供服务,备提供服务。
也就是说,工作在抢占模式下,不分主备,只管优先级。

如上配置,不管keepalived.conf里的state配置成master还是backup,只看谁的priority优先级高(一般而言,state为MASTER的优先级要高于BACKUP)。
priority优先级高的那一个在故障恢复后,会自动将VIP资源再次抢占回来!!

2)非抢占模式:
这种方式通过参数nopreempt(一般设置在advert_int的那一行下面)来控制。不管priority优先级,只要MASTER机器发生故障,VIP资源就会被切换到BACKUP上。
并且当MASTER机器恢复后,也不会去将VIP资源抢占回来,直至BACKUP机器发生故障时,才能自动切换回来。

千万注意: 
nopreempt这个参数只能用于state为backup的情况,所以在配置的时候要把master和backup的state都设置成backup,这样才会实现keepalived的非抢占模式!

也就是说:
a)当state状态一个为master,一个为backup的时候,加不加nopreempt这个参数都是一样的效果。即都是根据priority优先级来决定谁抢占vip资源的,是抢占模式!
b)当state状态都设置成backup,如果不配置nopreempt参数,那么也是看priority优先级决定谁抢占vip资源,即也是抢占模式。
c)当state状态都设置成backup,如果配置nopreempt参数,那么就不会去考虑priority优先级了,是非抢占模式!即只有vip当前所在机器发生故障,另一台机器才能接管vip。即使优先级高的那一台机器恢复  后也不会主动抢回vip,只能等到对方发生故障,才会将vip切回来。

---------------------------------mysql状态检测脚本优化---------------------------------

上面的mysql监测脚本有点过于简单且粗暴,即脚本一旦监测到Master的mysql服务关闭,就立刻把keepalived服务关闭,从而实现vip转移!

下面对该脚本进行优化,优化后,当监测到Master的mysql服务关闭后,就会将vip切换到Backup上(但此时Master的keepalived服务不会被暴力kill)
当Master的mysql服务恢复后,就会再次将VIP资源切回来!

[root@master ~]# cat /opt/chk_mysql.sh
#!/bin/bash
MYSQL=/usr/local/mysql/bin/mysql
MYSQL_HOST=localhost
MYSQL_USER=root
MYSQL_PASSWORD=123456
CHECK_TIME=3
 
#mysql  is working MYSQL_OK is 1 , mysql down MYSQL_OK is 0
 
MYSQL_OK=1
 
function check_mysql_helth (){
    $MYSQL -h $MYSQL_HOST -u $MYSQL_USER -p${MYSQL_PASSWORD} -e "show status;" >/dev/null 2>&1
    if [ $? = 0 ] ;then
    MYSQL_OK=1
    else
    MYSQL_OK=0
    fi
    return $MYSQL_OK
}
while [ $CHECK_TIME -ne 0 ]
do
    let "CHECK_TIME -= 1"
    check_mysql_helth
if [ $MYSQL_OK = 1 ] ; then
    CHECK_TIME=0
    exit 0
fi
if [ $MYSQL_OK -eq 0 ] &&  [ $CHECK_TIME -eq 0 ]
then
    pkill keepalived
    exit 1
fi
sleep 1
done

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