MySQL高可用之MHA_jqu219

其中master对外提供写服务，备选master（实际的slave，主机名slave1）提供读服务，slave也提供相关的读 服务，一旦master宕机，将会把备选master提升为新的master，slave指向新的master，manager作为管理服务 器。

一、开始部署
注：时间要同步

#在四台机器都配置epel源
[root@manager ~]# wget -O /etc/yum.repos.d/epel.repo http://mirrors.aliyun.com/repo/epel-7.repo

#建立ssh无交互登录环境 
#Manager主机：
[root@manager ~]# ssh-keygen -t rsa
Generating public/private rsa key pair.
Enter file in which to save the key (/root/.ssh/id\_rsa): 
Created directory '/root/.ssh'.
Enter passphrase (empty for no passphrase): 
Enter same passphrase again: 
Your identification has been saved in /root/.ssh/id\_rsa.
Your public key has been saved in /root/.ssh/id\_rsa.pub.
The key fingerprint is:
1c:cb:2d:4f:b1:80:ea:80:35:3b:89:48:5f:09:eb:2e root@manager
The key's randomart image is:
+--[ RSA 2048]----+
|   .             |
|    o ..         |
| .o. o. o .      |
|o+o+.. o = o     |
|+ =o.   S +      |
|  .+     +       |
| E ..     .      |
|  .              |
|                 |
+-----------------+
[root@manager ~]# for i in manager master slave1 slave2;do ssh-copy-id -i $i;done                    # 分发到其他主机
#master主机
[root@master ~]# ssh-keygen -t rsa
[root@master ~]# for i in manager master slave1 slave2;do ssh-copy-id -i $i;done
#slave1主机
[root@slave1 ~]# ssh-keygen -t rsa
[root@slave1 ~]# for i in manager master slave1 slave2;do ssh-copy-id -i $i;done
#slave2主机
[root@slave2 ~]# ssh-keygen -t rsa
[root@slave2 ~]# for i in manager master slave1 slave2;do ssh-copy-id -i $i;done

测试ssh无交互登录

[root@manager ~]# for i in master manager slave1 slave2;do ssh $i hostname;done
master
manager
slave1
slave2
[root@manager ~]# ssh master
Last failed login: Thu Jul  2 17:05:01 CST 2020 from 192.168.171.150 on ssh:notty
There was 1 failed login attempt since the last successful login.
Last login: Thu Jul  2 16:57:27 2020 from 192.168.171.1
[root@master ~]# ssh slave1
Last login: Thu Jul  2 17:02:59 2020 from 192.168.171.1
[root@slave1 ~]# ssh slave2
Last login: Thu Jul  2 17:03:29 2020 from 192.168.171.1
#配置hosts环境
[root@manager ~]# vim /etc/hosts
192.168.171.150 manager
192.168.171.151 master
192.168.171.152 slave1
192.168.171.153 slave2
[root@manager ~]# scp /etc/hosts root@192.168.171.151:/etc/
[root@manager ~]# scp /etc/hosts root@192.168.171.152:/etc/
[root@manager ~]# scp /etc/hosts root@192.168.171.153:/etc/

二、配置mysql半同步复制
为了尽可能的减少主库硬件损坏宕机造成的数据丢失，因此在配置MHA的同时建议 配置成MySQL的半同步复制。

注：mysql半同步插件是由谷歌提供，具体位置/usr/local/mysql/lib/plugin/下：
一个是master用的semisync\_master.so；
一个是slave用的semisync\_slave.so；

分别在主从节点上安装相关的插件（master, Candicate master,slave）

#检测数据库是否支持动态载入
mysql>show variables like '%have\_dynamic%';
+----------------------+-------+
| Variable\_name        | Value |
+----------------------+-------+
| have\_dynamic\_loading | YES   |           # 显示yes表示支持
+----------------------+-------+
1 row in set (0.00 sec)
#所有mysql数据库服务器，安装半同步插件(semisync\_master.so,semisync\_slave.so)
#要切记是所有mysql数据库服务器上都需要安装，这里我就在这写了一台该怎么安装
mysql>INSTALL PLUGIN rpl\_semi\_sync\_master SONAME 'semisync\_master.so'; 
Query OK, 0 rows affected (0.01 sec)


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