一、概述 将主数据库中的DDL和DML操作通过二进制日志传输到从数据库上，然后将这些日志重新执行（重做）；从而使得从数据库的数据与主数据库保持一致。
二、实验 关闭核心防护和清空防火墙规则 setenforce 0 iptables -F 安装mysql不做演示了 调整配置文件（主服务器）
vi /etc/my.cnf [client] port = 3306 default-character-set=utf8 socket = /usr/local/mysql/mysql.sock [mysql] port = 3306 default-character-set=utf8 socket = /usr/local/mysql/mysql.sock [mysqld] user = mysql basedir = /usr/local/mysql datadir = /usr/local/mysql/data port = 3306 character_set_server=utf8 pid-file = /usr/local/mysql/mysqld.pid socket = /usr/local/mysql/mysql.sock server-id = 1 //各服务器的server-id不能相同 log-bin = master-bin //新增，开启二进制文件功能 log-slave-updates = true //新增，用来控制是否写入二进制文件即允许同步 sql_mode=NO_ENGINE_SUBSTITUTION,STRICT_TRANS_TABLES,NO_AUTO_CREATE_USER,NO_AUTO_VALUE_ON_ZERO,NO_ZERO_IN_DATE,NO_ZERO_DATE,ERROR_FOR_DIVISION_BY_ZERO,PIPES_AS_CONCAT,ANSI_QUOTES调整从服务器主配置文件
vi /etc/my.cnf server-id = 2 relay-log = relay-log-bin //新增，开启二进制文件 relay-log-index = slave-relay-bin.index //新增，中继重启MySQL服务
systemctl restart mysqld配置 MySQL 一主两从 mysql> grant replication slave on . to ‘myslave’@‘20.0.0.%’ identified by ‘123’; 在 Mysql1 主服务器上查看二进制文件和同步点
mysql> show master status; +-------------------+----------+--------------+------------------+-------------------+ | File | Position | Binlog_Do_DB | Binlog_Ignore_DB | Executed_Gtid_Set | +-------------------+----------+--------------+------------------+-------------------+ | master-bin.000001 | 1893 | | | | +-------------------+----------+--------------+------------------+-------------------+接下来在 Mysql2 和 Mysql3 分别执行同步。
mysql> change master to master_host='20.0.0.130',master_user='myslave',master_password='123',master_log_file='master-bin.000001',master_log_pos=1893; mysql> start slave;查看 IO 和 SQL 线程都是 yes 代表同步正常。
mysql> show slave status\G; Slave_IO_Running: Yes Slave_SQL_Running: Yes问题：Slave_IO_Running: connecting 我的原因是核心防护未关，防火墙规则未清空 验证主从复制 在主服务器上创建一个数据库，可以在从服务器上同步看到
