Slave failed to initialize relay log info structure from the repository, Error_code: 1872

在一台主机上增加一个slave，启动的时候报
[ERROR] Slave SQL: Slave failed to initialize relay log info structure from the repository, Error_code: 1872

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=/db/mysql56/logs/relay_98_3326

2. reset slave
mysql>reset slave

mysql>change master to
master_host='192.168.0.38',
master_user='repl',
master_password='slave',
master_port=3306,
master_log_file='mysql-bin.001229',
master_log_pos=15970007;

mysql>start slave;