1、一主一从分配
环境：CentOS7 + Percona-Server-server-57-5.7.32
MySQL安装请参考博文：CentOS7下MySQL(Percona-Server-5.7)安装及简单使用。
主：192.168.178.130
从：192.168.178.150
2、主数据库master配置
1.修改mysql配置
找到主数据库的配置文件my.cnf(或者my.ini)，我的在/etc/percona-server.conf.d/mysqld.cnf下，相关配置项如下：
# 开启二进制日志
log_bin=mysql-bin
binlog_format=ROW
# 设置server-id
server-id=130
# 同步的数据库
binlog-do-db=test
# 不同步哪些数据库
binlog-ignore-db = mysql
binlog-ignore-db = information_schema
datadir=/var/lib/mysql socket=/var/lib/mysql/mysql.sock
symbolic-links=0
log-error=/var/log/mysqld.log
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修改完后需要重启mysql：
2.创建用于同步的用户账号
打开mysql会话:
创建用户并授权:
用户：repl 密码：123456
mysql> CREATE USER 'repl'@'localhost' IDENTIFIED BY '123456';
mysql> GRANT REPLICATION SLAVE ON *.* TO 'repl'@'localhost';
mysql> flush privileges;
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3.查看master状态
mysql> show master status;
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记录二进制文件名(mysql-bin.000001)和位置(763)。
3、从服务器slave配置
1.修改mysql配置
同样找到my.cnf配置文件，server-id=150，最终配置如下：
[mysqld]
log_bin=mysql-bin
binlog_format=ROW
server-id=150
#打开MySQL中继日志
#relay-log-index=slave-relay-bin.index
#relay-log=slave-relay-bin
datadir=/var/lib/mysql
socket=/var/lib/mysql/mysql.sock
symbolic-links=0
log-error=/var/log/mysqld.log
pid-file=/var/run/mysqld/mysqld.pid
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修改配置后重启mysql。
2.执行同步SQL语句
打开mysql会话，执行同步SQL语句(需要主服务器主机名，登陆账号，二进制文件的名称和位置)：
mysql> CHANGE MASTER TO MASTER_HOST='192.168.178.130',MASTER_USER='repl',MASTER_PASSWORD='123456',MASTER_LOG_FILE='mysql-bin.000001',MASTER_LOG_POS=763;
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3.启动slave同步进程：
4.查看slave状态
mysql> show slave status\G;
mysql> show slave status\G;
*************************** 1. row ***************************
Slave_IO_State:
Master_Host: 192.168.178.130
Master_User: repl
Master_Port: 3306
Connect_Retry: 60
Master_Log_File: mysql-bin.000004
Read_Master_Log_Pos: 154
Relay_Log_File: 192-relay-bin.000001
Relay_Log_Pos: 4
Relay_Master_Log_File: mysql-bin.000004
Slave_IO_Running: No
Slave_SQL_Running: Yes
Replicate_Do_DB:
Replicate_Ignore_DB:
Replicate_Do_Table:
Replicate_Ignore_Table:
Replicate_Wild_Do_Table:
Replicate_Wild_Ignore_Table:
Last_Errno: 0
Last_Error:
Skip_Counter: 0
Exec_Master_Log_Pos: 154
Relay_Log_Space: 154
Until_Condition: None
Until_Log_File:
Until_Log_Pos: 0
Master_SSL_Allowed: No
Master_SSL_CA_File:
Master_SSL_CA_Path:
Master_SSL_Cert:
Master_SSL_Cipher:
Master_SSL_Key:
Seconds_Behind_Master: NULL
Master_SSL_Verify_Server_Cert: No
Last_IO_Errno: 1593
Last_IO_Error: Fatal error: The slave I/O thread stops because master and slave have equal MySQL server UUIDs; these UUIDs must be different for replication to work.
Last_SQL_Errno: 0
Last_SQL_Error:
Replicate_Ignore_Server_Ids:
Master_Server_Id: 130
Master_UUID:
Master_Info_File: /var/lib/mysql/master.info
SQL_Delay: 0
SQL_Remaining_Delay: NULL
Slave_SQL_Running_State: Slave has read all relay log; waiting for more updates
Master_Retry_Count: 86400
Master_Bind:
Last_IO_Error_Timestamp: 210102 23:03:33
Last_SQL_Error_Timestamp:
Master_SSL_Crl:
Master_SSL_Crlpath:
Retrieved_Gtid_Set:
Executed_Gtid_Set:
Auto_Position: 0
Replicate_Rewrite_DB:
Channel_Name:
Master_TLS_Version:
1 row in set (0.00 sec)
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检查从库是否同步成功：
‘Slave_IO_Running: Yes’ (负责与主库同步IO通信)
‘Slave_SQL_Running: Yes’ (负责自身slave mysql进程)
上面有一处异常：
Last_IO_Error: Fatal error: The slave I/O thread stops because master and slave have equal MySQL server UUIDs; these UUIDs must be different for replication to work.
原因分析：
mysql 5.7的复制引入了uuid的概念，各个复制结构中的server_uuid得保证不一样，但是查看到直接copy data文件夹后server_uuid是相同的
mysql> show variables like ‘%server_uuid%’;
解决方法：
找到data文件夹下的auto.cnf文件，修改里面的uuid值，保证各个db的uuid不一样，重启mysql即可。
再次查看slave状态：
mysql> show slave status\G;
*************************** 1. row ***************************
Slave_IO_State: Waiting for master to send event
Master_Host: 192.168.178.130
Master_User: repl
Master_Port: 3306
Connect_Retry: 60
Master_Log_File: mysql-bin.000004
Read_Master_Log_Pos: 154
Relay_Log_File: 192-relay-bin.000003
Relay_Log_Pos: 320
Relay_Master_Log_File: mysql-bin.000004
Slave_IO_Running: Yes
Slave_SQL_Running: Yes
Replicate_Do_DB:
Replicate_Ignore_DB:
Replicate_Do_Table:
Replicate_Ignore_Table:
Replicate_Wild_Do_Table:
Replicate_Wild_Ignore_Table:
Last_Errno: 0
Last_Error:
Skip_Counter: 0
Exec_Master_Log_Pos: 154
Relay_Log_Space: 525
Until_Condition: None
Until_Log_File:
Until_Log_Pos: 0
Master_SSL_Allowed: No
Master_SSL_CA_File:
Master_SSL_CA_Path:
Master_SSL_Cert:
Master_SSL_Cipher:
Master_SSL_Key:
Seconds_Behind_Master: 0
Master_SSL_Verify_Server_Cert: No
Last_IO_Errno: 0
Last_IO_Error:
Last_SQL_Errno: 0
Last_SQL_Error:
Replicate_Ignore_Server_Ids:
Master_Server_Id: 130
Master_UUID: fb6c6f2b-4ca3-11eb-9e30-000c293fa755
Master_Info_File: /var/lib/mysql/master.info
SQL_Delay: 0
SQL_Remaining_Delay: NULL
Slave_SQL_Running_State: Slave has read all relay log; waiting for more updates
Master_Retry_Count: 86400
Master_Bind:
Last_IO_Error_Timestamp:
Last_SQL_Error_Timestamp:
Master_SSL_Crl:
Master_SSL_Crlpath:
Retrieved_Gtid_Set:
Executed_Gtid_Set:
Auto_Position: 0
Replicate_Rewrite_DB:
Channel_Name:
Master_TLS_Version:
1 row in set (0.02 sec)
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4、主从同步测试
登录主mysql（192.168.178.130）, 创建数据库test:
mysql> create database test;
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登录从mysql（192.168.178.150），查看数据库：
在主mysql上test数据库中新建表tb_user；
CREATE TABLE `tb_user` (
`id` int(11) NOT NULL AUTO_INCREMENT,
`user_name` varchar(20) DEFAULT '',
`passwd` varchar(20) DEFAULT NULL,
`age` smallint(6) DEFAULT NULL,
PRIMARY KEY (`id`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4;
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查看从mysql test数据库下的表：
在主mysql上tb_user上新增一条数据：
INSERT INTO tb_user (id, user_name, passwd, age) VALUES (1, 'xiaowang', '123456', 18);
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在从数据库上查看：
会看到主数据库上的操作都同步到了从数据库上。
按照目前的配置，从数据库也是可以写入数据的，但从的写入不会同步到主，会导致主从数据不一致;
从库上限制用户写入数据，在从服务中将read_only参数的值设为1：
mysql> set global read_only=1;
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生产上建议在主库上写数据，从库上读数据，这样就可以做到读写分离。
