Mysql slave 主從同步異常處理 Error：1872

1、報錯原因：

今日收到zabbix磁盤報警，通過du命令查找到mysql目錄過大，發現relay日誌沒有設置過期時間，所以手動刪除從庫中繼日誌，之後重啓mysql後主從複製狀態異常：

 du  -h --max-depth=1 / |sort   #查看根目錄下各目錄大小，並進行排序

2、報錯信息：

    [ERROR] Slave SQL: Slave failed to initialize relay log info structure from the repository, Error_code: 1872  

3、查看mstaer log日誌記錄點

mysql> show master status \G
*************************** 1. row ***************************
             File: mysql-bin.000033
         Position: 199787569
     Binlog_Do_DB: 
 Binlog_Ignore_DB: 
Executed_Gtid_Set: 950c9b3d-737f-11e7-8956-000c29fb7e00:1-38188942
1 row in set (0.00 sec)

mysql> show master status;
+------------------+-----------+--------------+------------------+-------------------------------------------------+
| File             | Position  | Binlog_Do_DB | Binlog_Ignore_DB | Executed_Gtid_Set                               |
+------------------+-----------+--------------+------------------+-------------------------------------------------+
| mysql-bin.000033 | 199787569 |              |                  | 950c9b3d-737f-11e7-8956-000c29fb7e00:1-38188942 |
+------------------+-----------+--------------+------------------+-------------------------------------------------+
1 row in set (0.00 sec)

4、由於是rm刪除中繼日誌，導致mysql無法進一步處理相關日誌，此時需要停掉slave stop 然後 reset初始化

通過上面的報錯以及relay log介紹，很容易知道由於mysql.slave_relay_log_info表中保留了以前的複製信息，導致新從庫啓動時無法找到對應文件，那麼我們清理掉該表中的記錄不就可以了。再次提醒，不要手動刪該表數據，MySQL已經提供工具給我們了：reset slave：

mysql>reset slave   

mysql>change master to master_log_file='mysql-bin.000033',master_log_pos=199787569 ;   #與masterbinlog點進行關聯
mysql>start slave;  

4.1 reset slave功能介紹：

1、刪除slave_master_info ，slave_relay_log_info兩個表中數據；
2、刪除所有relay log文件，並重新創建新的relay log文件；
3、不會改變gtid_executed 或者 gtid_purged的值

5、 驗證主從狀態

mysql> show slave status\G
*************************** 1. row ***************************
               Slave_IO_State: Waiting for master to send event
                  Master_Host: 192.168.0.37  #master主庫
                  Master_User: rep
                  Master_Port: 3306
                Connect_Retry: 60
              Master_Log_File: mysql-bin.000033
          Read_Master_Log_Pos: 199850445
               Relay_Log_File: DB03-relay-bin.000003
                Relay_Log_Pos: 25581
        Relay_Master_Log_File: mysql-bin.000033
             Slave_IO_Running: Yes  #主要看這裏
            Slave_SQL_Running: Yes  #主要這裏
              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: 199850445
              Relay_Log_Space: 25958
              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
                  Master_UUID: 950c9b3d-737f-11e7-8956-000c29fb7e00
             Master_Info_File: /application/mysql-5.6.35/data/master.info
                    SQL_Delay: 0
          SQL_Remaining_Delay: NULL
      Slave_SQL_Running_State: Slave has read all relay log; waiting for the slave I/O thread to update it
           Master_Retry_Count: 86400
                  Master_Bind: 
      Last_IO_Error_Timestamp: 
     Last_SQL_Error_Timestamp: 
               Master_SSL_Crl: 
           Master_SSL_Crlpath: 
           Retrieved_Gtid_Set: 950c9b3d-737f-11e7-8956-000c29fb7e00:38188963-38188981
            Executed_Gtid_Set: 291d8a91-75f5-11e7-995f-000c29ea7194:1-8,
950c9b3d-737f-11e7-8956-000c29fb7e00:1-38188981
                Auto_Position: 1
1 row in set (0.00 sec)