原理：建立两个数据库，库中生成两个线程（i/o ，SQL）。
主库中i/o线程会将修改的数据保存在二进制bin-log文件中，而从库也会开启i/o线程从而将主库上bin-log日志文件写到本地的Realy log（中继日志）里面。
从服务器上面同时开启一个 SQL 线程，定时检查 Realy log，如果有更新立即把更新的内容在本机的数据库上面执行一遍。从而最后主从库达成一致。
步骤：
主服务器(192.168.140.145):
1.进入mysql配置文件中在【mysqld】添加如下内容
vim /etc/my.cnf
[mysqld]
bin-log=/var/log/mysql/mysql-bin
sever-id=1
mkdir /var/log/mysql
chown -R mysql.mysql /var/log/mysql
systemctl restart mysqld
3.建立个用户,并授权
mysqld -uroot -pWww.2.com
mysql> grant replication slave on *.* 'wdx'@'%' identified by 'Www.2.com';
4.导出数据,并远程拷贝到从服务器192.168.140.146
mysqldump --all-databases --master-data=1 --user=root --password=Www.2.com >dump.sql
scp dump.sql root@192.168.140.146:/root/
从服务器(192.168.140.146):
用新建用户登入数据库测试
mysql -uwdx -pWww.2.com -h192.168.140.145
1.导入数据库
mysql -uroot -pWww.2.com < dump.sql
mysql -uroot -pWww.2.com
mysql> change master to
->master_host='192.168.140.145',
->master_user='wdx',
->master_password='Www.2.com',
->master_log_file=''mysql-bin.000001'
-> master_log_pos=600;
mysql>start slave;
mysql>show slave status\G
*************************** 1. row ***************************
Slave_IO_State: Waiting for master to send event
Master_Host: 192.168.140.145
Master_User: wdx
Master_Port: 3306
Connect_Retry: 60
Master_Log_File: mysql-bin.000001
Read_Master_Log_Pos: 600
Relay_Log_File: localhost-relay-bin.000002
Relay_Log_Pos: 320
Relay_Master_Log_File: mysql-bin.000001
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: 600
Relay_Log_Space: 531
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: 1
Master_UUID: 23be8b2a-2ddd-11e9-b5ba-000c29e25853
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 (0.00 sec)
