基本策略：

此时需要在主服务器上先完全备份，还原到从服务器；接着开启主从复制；
如果直接使用主从复制，那么主从服务器的压力很大；

主服务器数据全备份操作：

[root@master ~]$mysqldump -A -F --single-transaction --master-data=1 > all.sql

主服务器模拟修改操作：

MariaDB [(none)]> create database wangdb1;
Query OK, 1 row affected (0.01 sec)MariaDB [(none)]> show master logs;
+--------------------+-----------+
| Log_name           | File_size |
+--------------------+-----------+
| mariadb-bin.000001 |      8217 |
| mariadb-bin.000002 |       555 |
| mariadb-bin.000003 |       334 |
+--------------------+-----------+
3 rows in set (0.00 sec)[root@master ~]$less all.sql
CHANGE MASTER TO MASTER_LOG_FILE='mariadb-bin.000003', MASTER_LOG_POS=245;

主服务器配置：

[root@slave ~]$vim /etc/my.cnf
[mysqld]
datadir=/var/lib/mysql
socket=/var/lib/mysql/mysql.sock
# Disabling symbolic-links is recommended to prevent assorted security risks
symbolic-links=0
# Settings user and group are ignored when systemd is used.
innodb_file_per_table
server_id=2

从服务器数据还原：

[root@master ~]$scp all.sql 192.168.27.17:~[root@slave ~]$mysql < all.sql

从服务器开启主从复制：

MariaDB [(none)]> CHANGE MASTER TO-> MASTER_HOST='192.168.27.7',-> MASTER_USER='repluser',-> MASTER_PASSWORD='centos',-> MASTER_LOG_FILE='mariadb-bin.000003',-> MASTER_LOG_POS=245;
Query OK, 0 rows affected (0.01 sec)MariaDB [(none)]> start slave;
Query OK, 0 rows affected (0.00 sec)MariaDB [(none)]> show slave status\G
*************************** 1. row ***************************Slave_IO_State: Waiting for master to send eventMaster_Host: 192.168.27.7Master_User: repluserMaster_Port: 3306Connect_Retry: 60Master_Log_File: mariadb-bin.000003Read_Master_Log_Pos: 334Relay_Log_File: mariadb-relay-bin.000002Relay_Log_Pos: 620Relay_Master_Log_File: mariadb-bin.000003Slave_IO_Running: YesSlave_SQL_Running: YesReplicate_Do_DB: Replicate_Ignore_DB: Replicate_Do_Table: Replicate_Ignore_Table: Replicate_Wild_Do_Table: Replicate_Wild_Ignore_Table: Last_Errno: 0Last_Error: Skip_Counter: 0Exec_Master_Log_Pos: 334Relay_Log_Space: 916Until_Condition: NoneUntil_Log_File: Until_Log_Pos: 0Master_SSL_Allowed: NoMaster_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: NoLast_IO_Errno: 0Last_IO_Error: Last_SQL_Errno: 0Last_SQL_Error: Replicate_Ignore_Server_Ids: Master_Server_Id: 1
1 row in set (0.00 sec)

从服务器数据一致性保证：

由于从服务器上的数据也是可以被删除的，所以为了保证数据的一致性，可以将只读属性打开；
这种情况下，MySQL的root用户依然是可以修改删除的，只是对于普通用户生效；MariaDB [(none)]> show variables like 'read_only';+---------------+-------+| Variable_name | Value |+---------------+-------+| read_only     | OFF   |+---------------+-------+1 row in set (0.00 sec)[root@slave ~]$vim /etc/my.cnf
[mysqld]
datadir=/var/lib/mysql
socket=/var/lib/mysql/mysql.sock
# Disabling symbolic-links is recommended to prevent assorted security risks
symbolic-links=0
# Settings user and group are ignored when systemd is used.
innodb_file_per_table
server_id=2
read_onlyMariaDB [(none)]> grant select,update,delete on *.* to test@'192.168.27.%' identified by 'centos';
Query OK, 0 rows affected (0.00 sec)[root@master ~]$mysql -utest -pcentos -h192.168.27.17MariaDB [hellodb]> select * from students where age='22';
+-------+---------------+-----+--------+---------+-----------+
| StuID | Name          | Age | Gender | ClassID | TeacherID |
+-------+---------------+-----+--------+---------+-----------+
|     1 | Shi Zhongyu   |  22 | M      |       2 |         3 |
|     2 | Shi Potian    |  22 | M      |       1 |         7 |
|    21 | Huang Yueying |  22 | F      |       6 |      NULL |
+-------+---------------+-----+--------+---------+-----------+
3 rows in set (0.00 sec)MariaDB [hellodb]> delete from students;
ERROR 1290 (HY000): The MariaDB server is running with the --read-only option so it cannot execute this statement