MySQL 主从失败报错：Last_SQL_Errno: 1594

一、主从报错 Relay log read failure

问题原因，MySQL主从使用的是kvm虚拟机，物理机超分严重，在负载高的情况下会kill掉占用资源最多的虚拟机，再启动后导致主从失败

mysql> show slave status \G
*************************** 1. row ***************************
               Slave_IO_State: Waiting for master to send event
                  Master_Host: 192.168.0.8
                  Master_User: rsync
                  Master_Port: 3310
                Connect_Retry: 60
              Master_Log_File: mysql-bin.004772
          Read_Master_Log_Pos: 850868066
               Relay_Log_File: mysql-relay-bin.5326697
                Relay_Log_Pos: 46202283
        Relay_Master_Log_File: mysql-bin.004772
             Slave_IO_Running: Yes
            Slave_SQL_Running: No
              Replicate_Do_DB: 
          Replicate_Ignore_DB: 
           Replicate_Do_Table: 
       Replicate_Ignore_Table: 
      Replicate_Wild_Do_Table: 
  Replicate_Wild_Ignore_Table: 
                   Last_Errno: 1594
                   Last_Error: Relay log read failure: Could not parse relay log event entry. The possible reasons are: the master's binary log is corrupted (you can check this by running 'mysqlbinlog' on the binary log), the slave's relay log is corrupted (you can check this by running 'mysqlbinlog' on the relay log), a network problem, or a bug in the master's or slave's MySQL code. If you want to check the master's binary log or slave's relay log, you will be able to know their names by issuing 'SHOW SLAVE STATUS' on this slave.
                 Skip_Counter: 0
          Exec_Master_Log_Pos: 516345810
              Relay_Log_Space: 380726348
              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: 0
                Last_IO_Error: 
               Last_SQL_Errno: 1594
               Last_SQL_Error: Relay log read failure: Could not parse relay log event entry. The possible reasons are: the master's binary log is corrupted (you can check this by running 'mysqlbinlog' on the binary log), the slave's relay log is corrupted (you can check this by running 'mysqlbinlog' on the relay log), a network problem, or a bug in the master's or slave's MySQL code. If you want to check the master's binary log or slave's relay log, you will be able to know their names by issuing 'SHOW SLAVE STATUS' on this slave.
  Replicate_Ignore_Server_Ids: 
             Master_Server_Id: 1
1 row in set (0.00 sec)

二、解决方法

在show slave status\G中找到如下信息，或者查看relay-log.info文件：
Relay_Master_Log_File: mysql-bin.004772    # slave库已读取的master的binlog
Exec_Master_Log_Pos: 516345810             # 在slave上已经执行的position位置点

停掉slave，以slave已经读取的binlog文件，和已经执行的position为起点，重新设置同步。
mysql> stop slave;
Query OK, 0 rows affected (0.08 sec)

mysql> change master to master_host='192.168.0.8', master_user='rsync',master_password='d25tgb33edc',master_port=3306,master_log_file='mysql-bin.004772',master_log_pos=516345810;
Query OK, 0 rows affected (1.03 sec)

mysql> start slave;
Query OK, 0 rows affected (0.41 sec)