假设有一个一主二从的环境,当主库M出现故障时,需要将其中一个从库S1切换为主库,同时将S2指向新的主库S1,如果可能,需要将故障的主库M修复并重置为新的从库。
搭建一主二从复制环境可参考:MySQL搭建主从复制环境。
下面将演示一主二从复制环境主从库的切换,具体如下:
1、环境信息;
- Mater:192.168.1.110
- Slave1:192.168.1.111
- Slave2:192.168.1.112
Mater:192.168.1.110 Slave1:192.168.1.111 Slave2:192.168.1.112
2、查看主备库状态;
Master库:
- mysql> show processlist;
- +----+------+---------------------+------+-------------+------+---------------------------------------------------------------+------------------+
- | Id | User | Host | db | Command | Time | State | Info |
- +----+------+---------------------+------+-------------+------+---------------------------------------------------------------+------------------+
- | 2 | root | localhost | NULL | Query | 0 | starting | show processlist |
- | 3 | repl | 192.168.1.112:49819 | NULL | Binlog Dump | 207 | Master has sent all binlog to slave; waiting for more updates | NULL |
- | 4 | repl | 192.168.1.111:53017 | NULL | Binlog Dump | 165 | Master has sent all binlog to slave; waiting for more updates | NULL |
- +----+------+---------------------+------+-------------+------+---------------------------------------------------------------+------------------+
- 3 rows in set (0.00 sec)
- mysql> use test;
- Reading table information for completion of table and column names
- You can turn off this feature to get a quicker startup with -A
- Database changed
- mysql> select *from t_repl;
- +------+-------+---------------------+
- | id | name | cdate |
- +------+-------+---------------------+
- | 1 | Alen | 2018-03-04 17:56:57 |
- | 2 | Repl | 2018-03-04 20:10:45 |
- | 3 | USA | 2018-03-04 22:19:48 |
- | 4 | China | 2018-03-04 22:19:48 |
- | 5 | Japan | 2018-03-04 22:23:28 |
- | 6 | UK | 2018-03-04 22:23:28 |
- +------+-------+---------------------+
- 6 rows in set (0.00 sec)
- mysql> insert into t_repl(id,name) values(7,'Jacky'),(8,'Tom');
- Query OK, 2 rows affected (0.03 sec)
- Records: 2 Duplicates: 0 Warnings: 0
- mysql>
mysql> show processlist; +----+------+---------------------+------+-------------+------+---------------------------------------------------------------+------------------+ | Id | User | Host | db | Command | Time | State | Info | +----+------+---------------------+------+-------------+------+---------------------------------------------------------------+------------------+ | 2 | root | localhost | NULL | Query | 0 | starting | show processlist | | 3 | repl | 192.168.1.112:49819 | NULL | Binlog Dump | 207 | Master has sent all binlog to slave; waiting for more updates | NULL | | 4 | repl | 192.168.1.111:53017 | NULL | Binlog Dump | 165 | Master has sent all binlog to slave; waiting for more updates | NULL | +----+------+---------------------+------+-------------+------+---------------------------------------------------------------+------------------+ 3 rows in set (0.00 sec) mysql> use test; Reading table information for completion of table and column names You can turn off this feature to get a quicker startup with -A Database changed mysql> select *from t_repl; +------+-------+---------------------+ | id | name | cdate | +------+-------+---------------------+ | 1 | Alen | 2018-03-04 17:56:57 | | 2 | Repl | 2018-03-04 20:10:45 | | 3 | USA | 2018-03-04 22:19:48 | | 4 | China | 2018-03-04 22:19:48 | | 5 | Japan | 2018-03-04 22:23:28 | | 6 | UK | 2018-03-04 22:23:28 | +------+-------+---------------------+ 6 rows in set (0.00 sec) mysql> insert into t_repl(id,name) values(7,'Jacky'),(8,'Tom'); Query OK, 2 rows affected (0.03 sec) Records: 2 Duplicates: 0 Warnings: 0 mysql>
Slave1库:
- mysql> show processlist;
- +----+-------------+-----------+------+---------+------+--------------------------------------------------------+------------------+
- | Id | User | Host | db | Command | Time | State | Info |
- +----+-------------+-----------+------+---------+------+--------------------------------------------------------+------------------+
- | 1 | system user | | NULL | Connect | 299 | Waiting for master to send event | NULL |
- | 2 | system user | | NULL | Connect | 173 | Slave has read all relay log; waiting for more updates | NULL |
- | 4 | root | localhost | NULL | Query | 0 | starting | show processlist |
- +----+-------------+-----------+------+---------+------+--------------------------------------------------------+------------------+
- 3 rows in set (0.00 sec)
- mysql> use test;
- Reading table information for completion of table and column names
- You can turn off this feature to get a quicker startup with -A
- Database changed
- mysql> select *from t_repl;
- +------+-------+---------------------+
- | id | name | cdate |
- +------+-------+---------------------+
- | 1 | Alen | 2018-03-04 17:56:57 |
- | 2 | Repl | 2018-03-04 20:10:45 |
- | 3 | USA | 2018-03-04 22:19:48 |
- | 4 | China | 2018-03-04 22:19:48 |
- | 5 | Japan | 2018-03-04 22:23:28 |
- | 6 | UK | 2018-03-04 22:23:28 |
- | 7 | Jacky | 2018-03-05 18:55:32 |
- | 8 | Tom | 2018-03-05 18:55:32 |
- +------+-------+---------------------+
- 8 rows in set (0.00 sec)
- mysql>
mysql> show processlist; +----+-------------+-----------+------+---------+------+--------------------------------------------------------+------------------+ | Id | User | Host | db | Command | Time | State | Info | +----+-------------+-----------+------+---------+------+--------------------------------------------------------+------------------+ | 1 | system user | | NULL | Connect | 299 | Waiting for master to send event | NULL | | 2 | system user | | NULL | Connect | 173 | Slave has read all relay log; waiting for more updates | NULL | | 4 | root | localhost | NULL | Query | 0 | starting | show processlist | +----+-------------+-----------+------+---------+------+--------------------------------------------------------+------------------+ 3 rows in set (0.00 sec) mysql> use test; Reading table information for completion of table and column names You can turn off this feature to get a quicker startup with -A Database changed mysql> select *from t_repl; +------+-------+---------------------+ | id | name | cdate | +------+-------+---------------------+ | 1 | Alen | 2018-03-04 17:56:57 | | 2 | Repl | 2018-03-04 20:10:45 | | 3 | USA | 2018-03-04 22:19:48 | | 4 | China | 2018-03-04 22:19:48 | | 5 | Japan | 2018-03-04 22:23:28 | | 6 | UK | 2018-03-04 22:23:28 | | 7 | Jacky | 2018-03-05 18:55:32 | | 8 | Tom | 2018-03-05 18:55:32 | +------+-------+---------------------+ 8 rows in set (0.00 sec) mysql>
Slave2库:
- mysql> show processlist;
- +----+-------------+-----------+------+---------+------+--------------------------------------------------------+------------------+
- | Id | User | Host | db | Command | Time | State | Info |
- +----+-------------+-----------+------+---------+------+--------------------------------------------------------+------------------+
- | 1 | system user | | NULL | Connect | 356 | Waiting for master to send event | NULL |
- | 2 | system user | | NULL | Connect | 291 | Slave has read all relay log; waiting for more updates | NULL |
- | 4 | root | localhost | test | Query | 0 | starting | show processlist |
- +----+-------------+-----------+------+---------+------+--------------------------------------------------------+------------------+
- 3 rows in set (0.00 sec)
- mysql> select *from t_repl;
- +------+-------+---------------------+
- | id | name | cdate |
- +------+-------+---------------------+
- | 1 | Alen | 2018-03-04 17:56:57 |
- | 2 | Repl | 2018-03-04 20:10:45 |
- | 3 | USA | 2018-03-04 22:19:48 |
- | 4 | China | 2018-03-04 22:19:48 |
- | 5 | Japan | 2018-03-04 22:23:28 |
- | 6 | UK | 2018-03-04 22:23:28 |
- | 7 | Jacky | 2018-03-05 18:55:32 |
- | 8 | Tom | 2018-03-05 18:55:32 |
- +------+-------+---------------------+
- 8 rows in set (0.00 sec)
- mysql>
mysql> show processlist; +----+-------------+-----------+------+---------+------+--------------------------------------------------------+------------------+ | Id | User | Host | db | Command | Time | State | Info | +----+-------------+-----------+------+---------+------+--------------------------------------------------------+------------------+ | 1 | system user | | NULL | Connect | 356 | Waiting for master to send event | NULL | | 2 | system user | | NULL | Connect | 291 | Slave has read all relay log; waiting for more updates | NULL | | 4 | root | localhost | test | Query | 0 | starting | show processlist | +----+-------------+-----------+------+---------+------+--------------------------------------------------------+------------------+ 3 rows in set (0.00 sec) mysql> select *from t_repl; +------+-------+---------------------+ | id | name | cdate | +------+-------+---------------------+ | 1 | Alen | 2018-03-04 17:56:57 | | 2 | Repl | 2018-03-04 20:10:45 | | 3 | USA | 2018-03-04 22:19:48 | | 4 | China | 2018-03-04 22:19:48 | | 5 | Japan | 2018-03-04 22:23:28 | | 6 | UK | 2018-03-04 22:23:28 | | 7 | Jacky | 2018-03-05 18:55:32 | | 8 | Tom | 2018-03-05 18:55:32 | +------+-------+---------------------+ 8 rows in set (0.00 sec) mysql>
3、模拟主库Master宕机;
- mysql> shutdown;
- Query OK, 0 rows affected (0.01 sec)
- mysql> system service mysql.server status;
- ERROR! MySQL is not running, but lock file (/var/lock/subsys/mysql) exists
- mysql>
mysql> shutdown; Query OK, 0 rows affected (0.01 sec) mysql> system service mysql.server status; ERROR! MySQL is not running, but lock file (/var/lock/subsys/mysql) exists mysql>
4、确保从库都执行了relay log的全部更新,在每个从库上执行stop slave io_thread,然后检查show processlist的输出,状态是Slave has read all relay log; waiting for more updates,表示更新都执行完毕;
- mysql> stop slave io_thread;
- Query OK, 0 rows affected (0.01 sec)
- mysql> show processlist;
- +----+-------------+-----------+------+---------+------+--------------------------------------------------------+------------------+
- | Id | User | Host | db | Command | Time | State | Info |
- +----+-------------+-----------+------+---------+------+--------------------------------------------------------+------------------+
- | 2 | system user | | NULL | Connect | 7500 | Slave has read all relay log; waiting for more updates | NULL |
- | 4 | root | localhost | test | Query | 0 | starting | show processlist |
- +----+-------------+-----------+------+---------+------+--------------------------------------------------------+------------------+
- 2 rows in set (0.00 sec)
mysql> stop slave io_thread; Query OK, 0 rows affected (0.01 sec) mysql> show processlist; +----+-------------+-----------+------+---------+------+--------------------------------------------------------+------------------+ | Id | User | Host | db | Command | Time | State | Info | +----+-------------+-----------+------+---------+------+--------------------------------------------------------+------------------+ | 2 | system user | | NULL | Connect | 7500 | Slave has read all relay log; waiting for more updates | NULL | | 4 | root | localhost | test | Query | 0 | starting | show processlist | +----+-------------+-----------+------+---------+------+--------------------------------------------------------+------------------+ 2 rows in set (0.00 sec)
5、在从库Slave1上,执行stop slave来停止从服务,然后执行reset master重置成主库;
- mysql> show master status;
- Empty set (0.00 sec)
- mysql> stop slave;
- Query OK, 0 rows affected (0.00 sec)
- mysql> reset master;
- Query OK, 0 rows affected (0.00 sec)
mysql> show master status; Empty set (0.00 sec) mysql> stop slave; Query OK, 0 rows affected (0.00 sec) mysql> reset master; Query OK, 0 rows affected (0.00 sec)
6、检查从库Slave1的log-bin是否打开,没打开则打开;
7、删除从库Slave1上的master.info和relay-log.info,否则下次重启则按照从库启动;再/usr/lcoal/mysql/data目录下面
8、在Slave2上,执行stop slave停止从库服务,然后执行change master to重新指向主库slave1,再执行start slave启动从库;
注意再slave1上添加同步的账号
- mysql> stop slave;
- Query OK, 0 rows affected (0.01 sec)
- mysql> change master to
- -> master_host='192.168.1.111';
- Query OK, 0 rows affected (0.02 sec)
- mysql> start slave;
- Query OK, 0 rows affected (0.02 sec)
- mysql>
mysql> stop slave; Query OK, 0 rows affected (0.01 sec) mysql> change master to -> master_host='192.168.1.111'; Query OK, 0 rows affected (0.02 sec) mysql> start slave; Query OK, 0 rows affected (0.02 sec) mysql>
9、检查Slave2的状态,发现已经指向新的主库Slave1;
- mysql> show slave status\G;
- *************************** 1. row ***************************
- Slave_IO_State: Waiting for master to send event
- Master_Host: 192.168.1.111
- Master_User: repl
- Master_Port: 3306
- Connect_Retry: 60
- Master_Log_File: mysql111-bin.000002
- Read_Master_Log_Pos: 154
- Relay_Log_File: mysql-relay-bin.000003
- Relay_Log_Pos: 373
- Relay_Master_Log_File: mysql111-bin.000002
- 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: 799
- 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: 111
- Master_UUID: c8368e4a-1fa4-11e8-aa25-000c299f40a9
- Master_Info_File: /usr/local/mysql-5.7.21-linux-glibc2.12-x86_64/data/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)
- ERROR:
- No query specified
mysql> show slave status\G; *************************** 1. row *************************** Slave_IO_State: Waiting for master to send event Master_Host: 192.168.1.111 Master_User: repl Master_Port: 3306 Connect_Retry: 60 Master_Log_File: mysql111-bin.000002 Read_Master_Log_Pos: 154 Relay_Log_File: mysql-relay-bin.000003 Relay_Log_Pos: 373 Relay_Master_Log_File: mysql111-bin.000002 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: 799 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: 111 Master_UUID: c8368e4a-1fa4-11e8-aa25-000c299f40a9 Master_Info_File: /usr/local/mysql-5.7.21-linux-glibc2.12-x86_64/data/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) ERROR: No query specified
10、将应用程序指向新的主库Slave1,这样Slave1的所有更新写入到Slave1的Binlog中,从而同步到新的从库Slave2中;
新的主库Slave1:
- mysql> use test;
- Reading table information for completion of table and column names
- You can turn off this feature to get a quicker startup with -A
- Database changed
- mysql> select *from t_repl;
- +------+-------+---------------------+
- | id | name | cdate |
- +------+-------+---------------------+
- | 1 | Alen | 2018-03-04 17:56:57 |
- | 2 | Repl | 2018-03-04 20:10:45 |
- | 3 | USA | 2018-03-04 22:19:48 |
- | 4 | China | 2018-03-04 22:19:48 |
- | 5 | Japan | 2018-03-04 22:23:28 |
- | 6 | UK | 2018-03-04 22:23:28 |
- | 7 | Jacky | 2018-03-05 18:55:32 |
- | 8 | Tom | 2018-03-05 18:55:32 |
- +------+-------+---------------------+
- 8 rows in set (0.00 sec)
- mysql> insert into t_repl(id,name) values(9,'Slave1-->Master');
- Query OK, 1 row affected (0.01 sec)
- mysql>
mysql> use test; Reading table information for completion of table and column names You can turn off this feature to get a quicker startup with -A Database changed mysql> select *from t_repl; +------+-------+---------------------+ | id | name | cdate | +------+-------+---------------------+ | 1 | Alen | 2018-03-04 17:56:57 | | 2 | Repl | 2018-03-04 20:10:45 | | 3 | USA | 2018-03-04 22:19:48 | | 4 | China | 2018-03-04 22:19:48 | | 5 | Japan | 2018-03-04 22:23:28 | | 6 | UK | 2018-03-04 22:23:28 | | 7 | Jacky | 2018-03-05 18:55:32 | | 8 | Tom | 2018-03-05 18:55:32 | +------+-------+---------------------+ 8 rows in set (0.00 sec) mysql> insert into t_repl(id,name) values(9,'Slave1-->Master'); Query OK, 1 row affected (0.01 sec) mysql>
新的从库Slave2:
- mysql> use test ;
- Database changed
- mysql> select *from t_repl;
- +------+-----------------+---------------------+
- | id | name | cdate |
- +------+-----------------+---------------------+
- | 1 | Alen | 2018-03-04 17:56:57 |
- | 2 | Repl | 2018-03-04 20:10:45 |
- | 3 | USA | 2018-03-04 22:19:48 |
- | 4 | China | 2018-03-04 22:19:48 |
- | 5 | Japan | 2018-03-04 22:23:28 |
- | 6 | UK | 2018-03-04 22:23:28 |
- | 7 | Jacky | 2018-03-05 18:55:32 |
- | 8 | Tom | 2018-03-05 18:55:32 |
- | 9 | Slave1-->Master | 2018-03-05 21:28:54 |
- +------+-----------------+---------------------+
- 9 rows in set (0.00 sec)
mysql> use test ; Database changed mysql> select *from t_repl; +------+-----------------+---------------------+ | id | name | cdate | +------+-----------------+---------------------+ | 1 | Alen | 2018-03-04 17:56:57 | | 2 | Repl | 2018-03-04 20:10:45 | | 3 | USA | 2018-03-04 22:19:48 | | 4 | China | 2018-03-04 22:19:48 | | 5 | Japan | 2018-03-04 22:23:28 | | 6 | UK | 2018-03-04 22:23:28 | | 7 | Jacky | 2018-03-05 18:55:32 | | 8 | Tom | 2018-03-05 18:55:32 | | 9 | Slave1-->Master | 2018-03-05 21:28:54 | +------+-----------------+---------------------+ 9 rows in set (0.00 sec)
11、最后,如果主库Master修复,则将其重新配置成Slave1的从库;