change master to到一个不存在的主库或主库无法连接

向右看齐 2023-07-02 11:22 12阅读 0赞

本文测试当主库无法连接时，从库的复制状态。

## 1.设置主库 ##

在从库上， 将主库设置为`//127.0.0.1`或一个无法连接的主库：

MASTER_HOST='//127.0.0.1'

或

MASTER_HOST='_'

设置复制：

mysql> stop slave;
    Query OK, 0 rows affected (0.00 sec)
    
    mysql> 
    mysql> CHANGE MASTER TO MASTER_HOST='//127.0.0.1', MASTER_PORT=3306,MASTER_AUTO_POSITION=1;
    Query OK, 0 rows affected (0.01 sec)
    
    mysql> start slave;
    Query OK, 0 rows affected (0.00 sec)

## 2.查看复制状态 ##

mysql> show slave status\G
    *************************** 1. row ***************************
                   Slave_IO_State: Connecting to master
                      Master_Host: //127.0.0.1
                      Master_User: rep
                      Master_Port: 3306
                    Connect_Retry: 60
                  Master_Log_File: 
              Read_Master_Log_Pos: 4
                   Relay_Log_File: relay-bin.000001
                    Relay_Log_Pos: 4
            Relay_Master_Log_File: 
                 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: 0
                  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: 0
    Master_SSL_Verify_Server_Cert: No
                    Last_IO_Errno: 2005
                    Last_IO_Error: error connecting to master 'rep@//127.0.0.1:3306' - 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: mysql.slave_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: 200129 12:29:28
         Last_SQL_Error_Timestamp: 
                   Master_SSL_Crl: 
               Master_SSL_Crlpath: 
               Retrieved_Gtid_Set: 
                Executed_Gtid_Set: 43cf1658-41a4-11ea-9f90-080027974966:1-3
                    Auto_Position: 1
             Replicate_Rewrite_DB: 
                     Channel_Name: 
               Master_TLS_Version: 
    1 row in set (0.00 sec)

**IO线程状态**

主库无法连接，连接错误如下所示：

Slave_IO_State: Connecting to master
    Master_Host: //127.0.0.1
    Master_User: rep
    Master_Port: 3306

Slave_IO_Running: Connecting
    Slave_SQL_Running: Yes

Last_IO_Errno: 2005
    Last_IO_Error: error connecting to master 'rep@//127.0.0.1:3306' - retry-time: 60  retries: 1

可以看到，IO线程正在尝试连接主库。

**日志位点信息**

由于主库无法连接，日志位点相关的信息如下。

从库已经接收的主库日志位点信息：

Master_Log_File: 
    Read_Master_Log_Pos: 4

可以看到，日志文件为空，日志起点从4开始。

已经执行到的主库日志位点信息：