原理

1.环境搭建

1.需要两台服务器，如我的分别是：

1. -》 192.168.197.146---主库

2. -》 192.168.197.147---从库

2.分别关闭防火墙或者放行mysql端口号3306

如： systemctl stop firewalld

systemctl disable firewalld

2.配置主库：

1.在mysql的配置文件 /etc/my.cnf中添加：

server-id=1

read-only=0

2.重启mysql

systemctl restart mysql

如果重启中没有报错，就说明没有问题

3.登录mysql，创建远程连接的账号，并授予主从复制权限

mysql> create user 'redhat'@'%' identified with mysql_native_password by 'Root@123456';
Query OK, 0 rows affected (0.01 sec)

mysql> grant replication slave on *.* to 'redhat'@'%';
Query OK, 0 rows affected (0.00 sec)

mysql> show master status;

ps：

如果 show master status;没有东西，那么可能是你的二进制文件没有开启开关，5.6版本以上要手动指定。

如：在/etc/my.cnf中，添加：log-bin=mysqld-binlog

这样主库就配置好了

3.从库配置

1.在my.cnf中

server-id=2
read-only=1
#supper-read-only 指像超级管理员那样的权限

2.重启mysqld服务

systemctl restart mysqld

3.登陆从库的mysql，设置登陆配置：

mysql> change master to
-> master_host='192.168.197.146',
-> master_user='redhat',
-> master_password='Root@123456',
-> master_log_file='mysqld-binlog.000001',
-> master_log_pos=154;
Query OK, 0 rows affected, 2 warnings (0.01 sec)

4.开启同步操作：

start replica --8.0.22版本之后

start slave 8.0.22版本之前

5.查看同步操作：主要看下面两个是否为Yes，状态正常

mysql> show slave status\G
*************************** 1. row ***************************
Slave_IO_State: Connecting to master
Master_Host: 192.168.197.146
Master_User: bak
Master_Port: 3306
Connect_Retry: 60
Master_Log_File: mysqld-binlog.000001
Read_Master_Log_Pos: 154
Relay_Log_File: localhost-relay-bin.000001
Relay_Log_Pos: 4
Relay_Master_Log_File: mysqld-binlog.000001
Slave_IO_Running: Yes
Slave_SQL_Running: Yes.......

测试

在主库中创建数据库和表，并插入数据：

mysql> create database db01;
Query OK, 1 row affected (0.01 sec)

mysql> use db01;
Database changed

mysql> create table tb_user(

                id int(11) primary key not null auto_increment,

                 name varchar(50) not null,

                 sex varchar(1)

)engine=innodb default charset=utf8mb4;
Query OK, 0 rows affected (0.01 sec)

mysql> insert into tb_user values(null,'Tom','1'),(null,'Tigger','0'),(null,'Dawn','1');
Query OK, 3 rows affected (0.01 sec)
Records: 3 Duplicates: 0 Warnings: 0

mysql> show tables;
+----------------+
| Tables_in_db01 |
+----------------+
| tb_user |
+----------------+
1 row in set (0.00 sec)

mysql> select * from tb_user;
+----+--------+------+
| id | name | sex |
+----+--------+------+
| 1 | Tom | 1 |
| 2 | Tigger | 0 |
| 3 | Dawn | 1 |
+----+--------+------+
3 rows in set (0.00 sec)