如何查看mysql的gtid_mode_配置MHA开启主从同步的时候会提示从库gtid_mode为ON的状态…
通过MHA从库查看show slave status \G;会提示如下报错！
Last_IO_Error: The replication receiver thread cannot start because the master has GTID_MODE = ON and this server has GTID_MODE = OFF.
【报错原因】
MySQL的Master和Slave必须同时开启或者关闭enforce-gtid-consistency和gtid-mode功能，即要保持一致。
【解决方法】
mysql> set global gtid_mode=on;
ERROR 1788 (HY000): The value of @@GLOBAL.GTID_MODE can only be changed one step at a time: OFF OFF_PERMISSIVE ON_PERMISSIVE ON. Also note that this value must be stepped up or down simultaneously on all servers. See the Manual for instructions.
mysql> set global gtid_mode=OFF_PERMISSIVE;
Query OK, 0 rows affected (0.00 sec)
mysql> set global gtid_mode=ON_PERMISSIVE;
Query OK, 0 rows affected (0.02 sec)
mysql> set global gtid_mode=ON; 开启gtid之前 ，必须设置enforce_gtid_consistency=on
ERROR 3111 (HY000): SET @@GLOBAL.GTID_MODE = ON is not allowed because ENFORCE_GTID_CONSISTENCY is not ON.
mysql> set global enforce_gtid_consistency=on;
Query OK, 0 rows affected (0.00 sec)
mysql> set global gtid_mode=ON;
Query OK, 0 rows affected (0.01 sec)
【参考资料】
gtid-mode用来设置是否开启GTID功能，如果要开启GTID功能，需要同时开启log-bin和 log_slave_updates功能，另外还需要开启enforce_gtid_consistency功能。gtid_mode参数可以设置为 on、off、upgrade_step_1、upgrade_step_2四种值，其中upgrade_step_1和upgrade_step_2是 给将来mysql可能的新功能预留的，对当前的myql没有任何意义。同时，mysql建议在mysql_upgrade的时候，关闭gtid_mode 功能和enforce_gtid_consistency功能，因为Mysql在upgrade期间可能会操作非事务的MyISAM存储引擎表，会引起报 错。