很多时候，就算thread 正在进行，也不代表没有错误，一定要看看具体表示错误的变量
mysql> show slave statusG
*************************** 1. row ***************************
Slave_IO_State: Connecting to master
Master_Host: 192.168.1.107
Master_User: repl
Master_Port: 3306
Connect_Retry: 60
Master_Log_File: mysql-bin.000045
Read_Master_Log_Pos: 107
Relay_Log_File: CENTOS6-relay-bin.000001
Relay_Log_Pos: 4
Relay_Master_Log_File: mysql-bin.000045
Slave_IO_Running: Connecting
Slave_SQL_Running: Yes
Replicate_Do_DB:
Replicate_Ignore_DB:
Replicate_Do_Table:
Replicate_Ignore_Table:
Replicate_Wild_Do_Table:
Replicate_Wild_Ignore_Table:
Last_Errno: 0
Last_Error:
Skip_Counter: 0
Exec_Master_Log_Pos: 107
Relay_Log_Space: 107
Until_Condition: None
Until_Log_File:
Until_Log_Pos: 0
Master_SSL_Allowed: No
Master_SSL_CA_File:
Master_SSL_CA_Path:
Master_SSL_Cert:
Master_SSL_Cipher:
Master_SSL_Key:
Seconds_Behind_Master: NULL
Master_SSL_Verify_Server_Cert: No
Last_IO_Errno: 1045
Last_IO_Error: error connecting to master 'repl@192.168.1.107:3306' - retry-time: 60 retries: 86400
Last_SQL_Errno: 0
Last_SQL_Error:
Replicate_Ignore_Server_Ids:
Master_Server_Id: 0
row in set (0.00 sec)
一个变量可能承载不了那么多的错误信息，要看详细的错误信息就要看错误日志
160204 18:27:37 [Note] Error reading relay log event: slave SQL thread was killed 160204 18:27:37 [Note] Slave I/O thread killed while connecting to master 160204 18:27:37 [Note] Slave I/O thread exiting, read up to log 'mysql-bin.000045', position 107 160204 18:27:48 [Note] 'CHANGE MASTER TO executed'. Previous state master_host='centos7', master_port='3306', master_log_file='', master_log_pos='4'. New state master_host='192.168.1.107', master_port='3306', master_log_file='mysql-bin.000045', master_log_pos='107'. 160204 18:27:52 [Note] Slave SQL thread initialized, starting replication in log 'mysql-bin.000045' at position 107, relay log '/usr/local/mysql/data/CENTOS6-relay-bin.000001' position: 4 160204 18:27:52 [ERROR] Slave I/O: error connecting to master 'repl@192.168.1.107:3306' - retry-time: 60 retries: 86400, Error_code: 1045
不过也没有更多的信息，查一下错误代号
查询了一下master的登陆表
这句话的意思是，来自192.168.1.108这个地方的人，可以使用master机器上的一个叫做repl的账号，但是‘repl’@'192.168.1.108'这个账号可以做一些什么东西，不能做一些什么东西呢，这个需要看他的权限，也就是他的能力，因为可能不止一项权利，所以用了复数grants
可以看到它是没有经过授权的，我们现在可以对他授权，仅仅是一个“进行复制”的权利，授权完以后需要确认一下
现在重新使用replication功能，其实不需要start slave去开启，它自己就会自动开启的
mysql> show slave statusG
*************************** 1. row ***************************
Slave_IO_State: Waiting for master to send event
Master_Host: 192.168.1.107
Master_User: repl
Master_Port: 3306
Connect_Retry: 60
Master_Log_File: mysql-bin.000045
Read_Master_Log_Pos: 3220
Relay_Log_File: CENTOS6-relay-bin.000002
Relay_Log_Pos: 3366
Relay_Master_Log_File: mysql-bin.000045
Slave_IO_Running: Yes
Slave_SQL_Running: Yes
Replicate_Do_DB:
Replicate_Ignore_DB:
Replicate_Do_Table:
Replicate_Ignore_Table:
Replicate_Wild_Do_Table:
Replicate_Wild_Ignore_Table:
Last_Errno: 0
Last_Error:
Skip_Counter: 0
Exec_Master_Log_Pos: 3220
Relay_Log_Space: 3524
Until_Condition: None
Until_Log_File:
Until_Log_Pos: 0
Master_SSL_Allowed: No
Master_SSL_CA_File:
Master_SSL_CA_Path:
Master_SSL_Cert:
Master_SSL_Cipher:
Master_SSL_Key:
Seconds_Behind_Master: 0
Master_SSL_Verify_Server_Cert: No
Last_IO_Errno: 0
Last_IO_Error:
Last_SQL_Errno: 0
Last_SQL_Error:
Replicate_Ignore_Server_Ids:
Master_Server_Id: 1
1 row in set (0.00 sec)
原文来自https://www.cnblogs.com/hellotracy/articles/5183057.html