最近在部署MySQL主从复制架构的时候，，碰到了"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." 这个错误提示。即主从架构中使用了相同的UUID。检查server_id系统变量，已经是不同的设置，那原因是？接下来为具体描述。
1、错误消息mysql> show slave staus;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.2、查看主从的server_id变量master_mysql> show variables like ‘server_id’;+—————+——-+| Variable_name | Value |+—————+——-+| server_id| 33 |+—————+——-+slave_mysql> show variables like ‘server_id’;+—————+——-+| Variable_name | Value |+—————+——-+| server_id| 11 |+—————+——-+– 从上面的情形可知，主从mysql已经使用了不同的server_id3、解决故障###查看auto.cnf文件[root@dbsrv1 ~] cat /data/mysqldata/auto.cnf ### 主上的uuid[auto]server-uuid=62ee10aa-b1f7-11e4-90ae-080027615026[root@dbsrv2 ~]# more /data/mysqldata/auto.cnf ###从上的uuid，果然出现了重复，原因是克隆了虚拟机，只改server_id不行[auto]server-uuid=62ee10aa-b1f7-11e4-90ae-080027615026[root@dbsrv2 ~]# mv /data/mysqldata/auto.cnf /data/mysqldata/auto.cnf.bk ###重命名该文件[root@dbsrv2 ~]# service mysql restart###重启mysqlShutting down MySQL.[ OK ]Starting MySQL.[ OK ][root@dbsrv2 ~]# more /data/mysqldata/auto.cnf ###重启后自动生成新的auto.cnf文件，即新的UUID[auto]server-uuid=6ac0fdae-b5d7-11e4-a9f3-0800278ce5c9###再次查看slave的状态已经正常[root@dbsrv1 ~]# mysql -uroot -pxxx -e "show slave status\G"|grep RunningWarning: Using a password on the command line interface can be insecure.Slave_IO_Running: YesSlave_SQL_Running: YesSlave_SQL_Running_State: Slave has read all relay log; waiting for the slave I/O thread to update it###主库端查看自身的uuidmaster_mysql> show variables like ‘server_uuid’;+—————+————————————–+| Variable_name | Value|+—————+————————————–+| server_uuid | 62ee10aa-b1f7-11e4-90ae-080027615026 |+—————+————————————–+1 row in set (0.00 sec)###主库端查看从库的uuidmaster_mysql> show slave hosts;+———–+——+——+———–+————————————–+| Server_id | Host | Port | Master_id | Slave_UUID|+———–+——+——+———–+————————————–+|33 || 3306 |11 | 62ee10aa-b1f7-11e4-90ae-080027615030 ||22 || 3306 |11 | 6ac0fdae-b5d7-11e4-a9f3-0800278ce5c9 |+———–+——+——+———–+————————————–+### Author : Leshami### Blog :
4、延生参考a、有关server_id的描述The server ID, used in replication to give each master and slave a unique identity. This variable is setby the –server-id option. For each server participating in replication, you should pick apositive integer in the range from 1 to 232– 1(2的32次方减1) to act as that server’s ID.
b、有关 server_uuid的描述Beginning with MySQL 5.6, the server generates a true UUID in addition to the –server-idsupplied by the user. This is available as the global, read-only variable server_uuid(全局只读变量)
When starting, the MySQL server automatically obtains a UUID as follows:a). Attempt to read and use the UUID written in the file data_dir/auto.cnf (where data_dir isthe server’s data directory); exit on success.b). Otherwise, generate a new UUID and save it to this file, creating the file if necessary.The auto.cnf file has a format similar to that used for my.cnf or my.ini files. In MySQL 5.6,auto.cnf has only a single [auto] section containing a single server_uuid [1992] setting andvalue;
ImportantThe auto.cnf file is automatically generated; you should not attempt to writeor modify this file
Also beginning with MySQL 5.6, when using MySQL replication, masters and slaves know oneanother’s UUIDs. The value of a slave’s UUID can be seen in the output of SHOW SLAVE HOSTS. OnceSTART SLAVE has been executed (but not before), the value of the master’s UUID is available on theslave in the output of SHOW SLAVE STATUS.
In MySQL 5.6.5 and later, a server’s server_uuid is also used in GTIDs for transactions originatingon that server. For more information, see Section 16.1.3, “Replication with Global Transaction
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