创建MySQL主从复制过程中，change master之后，启动slave复制，发现从库状态不正常。报如下错误：

mysql> show slave status\G
*************************** 1. row ***************************
               Slave_IO_State: Connecting to master
                  Master_Host: abcedeawstest-instance-7.chedandeheny.ap-northeast-7.rds.ama
                  Master_User: repl
                  Master_Port: 3336
                Connect_Retry: 60
              Master_Log_File: mysql-bin-changelog.000009
          Read_Master_Log_Pos: 60349807
               Relay_Log_File: relay-bin.000001
                Relay_Log_Pos: 4
        Relay_Master_Log_File: mysql-bin-changelog.000009
             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: 60349807
              Relay_Log_Space: 154
              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: 2005
                Last_IO_Error: error connecting to master 'repl@abcedeawstest-instance-7.chedandeheny.ap-northeast-7.rds.ama:3336' - retry-time: 60  retries: 1
               Last_SQL_Errno: 0
               Last_SQL_Error: 
  Replicate_Ignore_Server_Ids: 
             Master_Server_Id: 0
                  Master_UUID: 
             Master_Info_File: /data/master.info
                    SQL_Delay: 0
          SQL_Remaining_Delay: NULL
      Slave_SQL_Running_State: Slave has read all relay log; waiting for more updates
           Master_Retry_Count: 86400
                  Master_Bind: 
      Last_IO_Error_Timestamp: 211116 11:40:02
     Last_SQL_Error_Timestamp: 
               Master_SSL_Crl: 
           Master_SSL_Crlpath: 
           Retrieved_Gtid_Set: 
            Executed_Gtid_Set: 
                Auto_Position: 0
         Replicate_Rewrite_DB: 
                 Channel_Name: 
           Master_TLS_Version: 
1 row in set (0.00 sec)

mysql> 

　　

这里的错误编码是2005：

Error number: 2005; Symbol: CR_UNKNOWN_HOST;

Message: Unknown MySQL server host '%s' (%d)

　　

原因：
主机的主机域名太长。全称是：

abcedeawstest-instance-7.chedandeheny.ap-northeast-7.rds.amazonaws.com

　　

长度超过了60个字符，被截取成了：

abcedeawstest-instance-7.chedandeheny.ap-northeast-7.rds.ama

从而变成了一个不正确的主机名。这一点从show slave status的输出结果就可以看出。

 

解决方案：
将域名改成了服务器的IP地址,重新建立与主库的连接。