mysql> set global super_read_only=on;
Query OK, 0 rows affected (0.00 sec)mysql> set global read_only=on;
Query OK, 0 rows affected (0.00 sec)2、查看主备库数据是否一致
主库：
mysql> show master status;+------------------+----------+--------------+------------------+-----------------------------------------------+| File | Position | Binlog_Do_DB | Binlog_Ignore_DB | Executed_Gtid_Set |+------------------+----------+--------------+------------------+-----------------------------------------------+| mysql-bin.000012 | 195 | | | 8876d804-9218-11e8-8eaf-0242ac110002:1-224227 |+------------------+----------+--------------+------------------+-----------------------------------------------+1 row in set (0.00 sec)mysql> select @@server_uuid;+--------------------------------------+| @@server_uuid |+--------------------------------------+| 8876d804-9218-11e8-8eaf-0242ac110002 |+--------------------------------------+1 row in set (0.00 sec) 备库mysql> show slave status\G;*************************** 1. row *************************** Slave_IO_State: Waiting for master to send event Master_Host: 172.17.0.2 Master_User: repl Master_Port: 3306 Connect_Retry: 60 Master_Log_File: mysql-bin.000012 Read_Master_Log_Pos: 195 Relay_Log_File: relaylog.000018 Relay_Log_Pos: 409 Relay_Master_Log_File: mysql-bin.000012 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: 195 Relay_Log_Space: 672 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: 0Master_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: 23306 Master_UUID: 8876d804-9218-11e8-8eaf-0242ac110002 Master_Info_File: mysql.slave_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: 8876d804-9218-11e8-8eaf-0242ac110002:1-224227 Executed_Gtid_Set: 8876d804-9218-11e8-8eaf-0242ac110002:1-224227,febb1cb0-922f-11e8-ba72-0242ac110003:1-2 Auto_Position: 1 Replicate_Rewrite_DB: Channel_Name: mysq57-3306 Master_TLS_Version: Master_public_key_path: Get_master_public_key: 01 row in set (0.00 sec)ERROR:
No query specified#Retrieved_Gtid_Set ，Executed_Gtid_Set这2个值是否和主库的Executed_Gtid_Set 值相等，如果相等，则代表一致
3、备库:停止io_thread和sql_threadmysql> stop slave;Query OK, 0 rows affected (0.11 sec)4、备库：记录binlog的POS
mysql> show master status;+------------------+-----------+--------------+------------------+-------------------+| File | Position | Binlog_Do_DB | Binlog_Ignore_DB | Executed_Gtid_Set |+------------------+-----------+--------------+------------------+-------------------+| master2-bin.001 | 162644437 | | | |+------------------+-----------+--------------+------------------+-------------------+1 row in set (0.00 sec)mysql> flush logs;mysql> show master status;+------------------+-----------+--------------+------------------+-------------------+| File | Position | Binlog_Do_DB | Binlog_Ignore_DB | Executed_Gtid_Set |+------------------+-----------+--------------+------------------+-------------------+| master2-bin.002 | 163266389 | | | |+------------------+-----------+--------------+------------------+-------------------+1 row in set (0.00 sec)5、将备库只读模式关闭
mysql> show global variables like '%read_only%';
+-----------------------+-------+| Variable_name | Value |+-----------------------+-------+| innodb_read_only | OFF || read_only | ON || super_read_only | ON || transaction_read_only | OFF |+-----------------------+-------+4 rows in set (0.01 sec)mysql> set global super_read_only=off;
Query OK, 0 rows affected (0.00 sec)mysql> set global read_only=off;
Query OK, 0 rows affected (0.00 sec)mysql> show global variables like '%read_only%';
+-----------------------+-------+| Variable_name | Value |+-----------------------+-------+| innodb_read_only | OFF || read_only | OFF || super_read_only | OFF || transaction_read_only | OFF |+-----------------------+-------+4 rows in set (0.00 sec)6、新备库执行change master to语句,指向新主库
CHANGE MASTER 分2种情况，一种是开启了GTID模式，一种是未开启GTID模式GTID模式:
CHANGE MASTER TO
MASTER_HOST='oracle2.example.com', MASTER_USER='repl', MASTER_PASSWORD='password', MASTER_PORT=3306, MASTER_AUTO_POSITION=1;未开启GTID模式CHANGE MASTER TO
MASTER_HOST='oracle2.example.com', MASTER_USER='repl', MASTER_PASSWORD='password', MASTER_PORT=3306, MASTER_LOG_FILE='master2-bin.002', MASTER_LOG_POS=163266389;