MySQL的主从复制和MySQL的读写分离两者有着紧密联系，首先部署主从复制，只有主从复制完了，才能在此基础上进行数据的读写分离。简单来说，读写分离就是只在主服务器上写，只在从服务器上读，基本的原理是让主数据库处理事务性查询，而从数据库处理select查询，数据库复制被用来把事务性查询导 致的改变更新同步到集群中的从数据库。
一般来说都是通过 主从复制（Master-Slave）的方式来同步数据，再通过读写分离（MySQL-Proxy）来提升数据库的并发负载能力 这样的方案来进行部署与实施的。
配置环境
master机：server1（172.25.254.1）
slave机：server2(172.25.254.2)
调度器：server3（172.25.254.3）
1、调度器配置
1、安装读写分离代理mysql-proxy
[root@server3 ~]# ls
mysql-proxy-0.8.5-linux-el6-x86-64bit.tar.gz
[root@server3 ~]# tar zxf mysql-proxy-0.8.5-linux-el6-x86-64bit.tar.gz -C /usr/local/
[root@server3 ~]# cd /usr/local/
[root@server3 local]# ln -s mysql-proxy-0.8.5-linux-el6-x86-64bit/ mysql-proxy
[root@server3 local]# ll
total 44
drwxr-xr-x. 2 root root 4096 Jun 28 2011 bin
drwxr-xr-x. 2 root root 4096 Jun 28 2011 etc
drwxr-xr-x. 2 root root 4096 Jun 28 2011 games
drwxr-xr-x. 2 root root 4096 Jun 28 2011 include
drwxr-xr-x. 2 root root 4096 Jun 28 2011 lib
drwxr-xr-x. 2 root root 4096 Jun 28 2011 lib64
drwxr-xr-x. 2 root root 4096 Jun 28 2011 libexec
lrwxrwxrwx 1 root root 38 Jul 7 16:56 mysql-proxy -> mysql-proxy-0.8.5-linux-el6-x86-64bit/
drwxr-xr-x 8 7161 wheel 4096 Aug 19 2014 mysql-proxy-0.8.5-linux-el6-x86-64bit
drwxr-xr-x. 2 root root 4096 Jun 28 2011 sbin
drwxr-xr-x. 5 root root 4096 Jun 19 23:38 share
drwxr-xr-x. 2 root root 4096 Jun 28 2011 src2、为了测试读写分离效果，修改lua脚本
[root@server3 local]# cd mysql-proxy/share/doc/mysql-proxy/
[root@server3 mysql-proxy]# vim rw-splitting.lua
38 if not proxy.global.config.rwsplit then
39 proxy.global.config.rwsplit = {
40 min_idle_connections = 1,
41 max_idle_connections = 2, ##表示连接数超过两个就开始读写分离
42
43 is_debug = false
44 }
45 end3、编写配置文件
[root@server3 mysql-proxy]# pwd
/usr/local/mysql-proxy
[root@server3 mysql-proxy]# mkdir logs
[root@server3 mysql-proxy]# mkdir conf
[root@server3 mysql-proxy]# vim conf/mysql-proxy.conf
1 [mysql-proxy]
2 user=root
3 proxy-address=172.25.254.3:3306
4 proxy-read-only-backend-addresses=172.25.254.2:3306
5 proxy-backend-addresses=172.25.254.1:3306
6 proxy-lua-script=/usr/local/mysql-proxy/share/doc/mysql-proxy/rw-splitting.l ua
7 log-file=/usr/local/mysql-proxy/logs/mysql-proxy.log
8 log-level=debug
9 daemon=true
10 keepalive=true3、启动mysql-proxy
[root@server3 mysql-proxy]# /usr/local/mysql-proxy/bin/mysql-proxy --defaults-file=/usr/local/mysql-proxy/conf/mysql-proxy.conf ##第一次启动失败，原因是因为配置文件权限过大
2018-07-07 17:13:41: (critical) mysql-proxy-cli.c:326: loading config from '/usr/local/mysql-proxy/conf/mysql-proxy.conf' failed: permissions of /usr/local/mysql-proxy/conf/mysql-proxy.conf aren't secure (0660 or stricter required)
2018-07-07 17:13:41: (message) Initiating shutdown, requested from mysql-proxy-cli.c:328
2018-07-07 17:13:41: (message) shutting down normally, exit code is: 1
[root@server3 mysql-proxy]# chmod 550 conf/mysql-proxy.conf
[root@server3 mysql-proxy]# /usr/local/mysql-proxy/bin/mysql-proxy --defaults-file=/usr/local/mysql-proxy/conf/mysql-proxy.conf ##再次启动成功测试：
1、master机授权用户可远程登陆：
mysql> grant select,insert,update on user.* to root@'172.25.254.%' identified by 'Chao@199512';
Query OK, 0 rows affected, 1 warning (0.36 sec)2、master机和slave机安装lsof，以便查看效果
3、物理机拿三个shell测试
[root@foundation77 ~]# mysql -h 172.25.254.3 -uroot -p
Enter password:
Welcome to the MariaDB monitor. Commands end with ; or \g.
Your MySQL connection id is 9
Server version: 5.7.17-log MySQL Community Server (GPL)
Copyright (c) 2000, 2015, Oracle, MariaDB Corporation Ab and others.
Type 'help;' or '\h' for help. Type '\c' to clear the current input statement.
MySQL [(none)]> master机查看
[root@server1 ~]# lsof -i :3306
COMMAND PID USER FD TYPE DEVICE SIZE/OFF NODE NAME
mysqld 1168 mysql 34u IPv6 8487 0t0 TCP *:mysql (LISTEN)
mysqld 1168 mysql 52u IPv6 9264 0t0 TCP server1:mysql->server3:51667 (ESTABLISHED)
mysqld 1168 mysql 53u IPv6 9165 0t0 TCP server1:mysql->server2:57130 (ESTABLISHED)
mysqld 1168 mysql 55u IPv6 9265 0t0 TCP server1:mysql->server3:51668 (ESTABLISHED)slave机查看
[root@server2 ~]# lsof -i :3306
COMMAND PID USER FD TYPE DEVICE SIZE/OFF NODE NAME
mysqld 1705 mysql 32u IPv6 9424 0t0 TCP *:mysql (LISTEN)
mysqld 1705 mysql 48u IPv6 9577 0t0 TCP server2:mysql->server3:60675 (ESTABLISHED)
mysqld 1705 mysql 50u IPv4 9438 0t0 TCP server2:57130->server1:mysql (ESTABLISHED)我们在连接slave机的客户端上写入数据，看是否写入到master机，如果写入，表示读写分离成功
连接slave机客户端写入
MySQL [user]> show tables;
+----------------+
| Tables_in_user |
+----------------+
| usertb |
+----------------+
1 row in set (0.00 sec)
MySQL [user]> insert into user.usertn values('huge','23');
ERROR 1146 (42S02): Table 'user.usertn' doesn't exist
MySQL [user]> insert into user.usertb values('huge','23');
Query OK, 1 row affected (0.38 sec)master机查看
mysql> select * from user.usertb;
+-------------+-----+
| username | age |
+-------------+-----+
| wuyanzu | 18 |
| chenguanxi | 19 |
| zhoujielun | 20 |
| liudehua | 21 |
| zhangxueyou | 22 |
| huge | 23 |
+-------------+-----+
6 rows in set (0.00 sec)写入成功，读写分离效果实现