mysql主从同步配置好之后，数据没有同步，从数据库出现如下错误
mysql> show slave status \G;
*************************** 1. row ***************************
               Slave_IO_State: Connecting to master
                  Master_Host: 192.168.3.27
                  Master_User: backup
                  Master_Port: 3306
                Connect_Retry: 60
              Master_Log_File:
          Read_Master_Log_Pos: 4
               Relay_Log_File: localhost-relay-bin.000003
                Relay_Log_Pos: 4
        Relay_Master_Log_File:
            Slave_IO_Running: No
            Slave_SQL_Running: Yes
              Replicate_Do_DB: redmine
          Replicate_Ignore_DB: mysql
           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: 106
              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 'backup@192.168.3.27:3306' - retry-time: 60  retries: 86400
               Last_SQL_Errno: 0
               Last_SQL_Error:
1 row in set (0.00 sec)
ERROR:
No query specified
 
连接主数据库出错，但直接连接又是OK的
/usr/local/mysql/bin/mysql -ubackup -p123 -h 192.168.3.27
 
Slave_IO_Running: No
出现这个情况，有两种可能：
1、权限的设置问题，slave没有权限访问master
2、同步过程中出错
 
已经设置了权限了，可以排除第一点
grant replication slave on *.* to backup@192.168.3.25 identified by '123';
解决方法：
从服务器上删除掉所有的二进制日志文件，包括一个数据目录下的master.info文件和hostname-relay-bin开头的文件
master.info:：记录了Mysql主服务器上的日志文件和记录位置、连接的密码
 
删除之后，重启数据库，ok