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报错：
1）
change master导致的：
              last_io_error: error connecting to master 'repl1@ip:3306' - retry-time: 60  retries
2）    
在没有解锁的情况下停止slave进程：
     mysql> stop slave;
error 1192 (hy000): can't execute the given command because you have active locked tables or an active transaction
3）
change master语法错误，落下逗号
mysql> change master to
    -> master_host='ip'
    -> master_user='user',
    -> master_password='passwd',
    -> master_log_file='mysql-bin.000002',
    -> master_log_pos=106;
error 1064 (42000): you have an error in your sql syntax; check the manual that corresponds to your mysql server version for the right syntax to use near 'master_user='user',
master_password='passwd',
master_log_file='mysql-bin.000002' at line 3
4）
在没有停止slave进程的情况下change master
mysql> change master to master_host=‘ip', master_user='user', master_password='passwd', master_log_file='mysql-bin.000001',master_log_pos=106;
error 1198 (hy000): this operation cannot be performed with a running slave; run stop slave first
5）
a b的server-id相同：
last_io_error: fatal error: the slave i/o thread stops because master and slave have equal mysql server ids;
these ids must be different for replication to work (or the --replicate-same-server-id option must be used on
slave but this does not always make sense; please check the manual before using it).
查看server-id
mysql> show variables like 'server_id';
手动修改server-id
mysql> set global server_id=2; #此处的数值和my.cnf里设置的一样就行
mysql> slave start;
6）change master之后，查看slave的状态，发现slave_io_running 为no
需要注意的是，做完上述操作之后最后重启mysql进程
摘自：anljf的专栏
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