mysql5.7启动slave报错 ERROR 1872 (HY000): Slave failed to initialize relay log info structure from the repository

原因：检查my.cnf，原来没指定relay_log，mysql默认产生的relay_log名被该server上的另一个mysql slave占用了。

解决方法：
1.在my.cnf中添加

relay_log = /usr/local/mysql/log/relay.log

2. reset slave

mysql> reset slave;

mysql> change master  to
    -> master_host='192.168.0.11',
    -> master_user='rep',
    -> master_password='VkNI%5%-p,0^)s~';
Query OK, 0 rows affected, 2 warnings (0.19 sec)

mysql> start slave;
Query OK, 0 rows affected (0.03 sec)

mysql> show slave status\G;