[ERROR] Slave I/O: error connecting to master

刚配置的MySQL主从，在从机上看到
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mysql> SHOW slave STATUS \\G
*************************** 1. row ***************************
               Slave_IO_State: Connecting to master
                  Master_Host: 172.17.210.199
                  Master_User: my
                  Master_Port: 3306
                Connect_Retry: 60
              Master_Log_File: masters-bin.000003
          Read_Master_Log_Pos: 1224
               Relay_Log_File: testmysql-relay-bin.000001
                Relay_Log_Pos: 4
        Relay_Master_Log_File: masters-bin.000003
             Slave_IO_Running: Connecting
            Slave_SQL_Running: Yes
              Replicate_Do_DB:
          Replicate_Ignore_DB:
看日志有很多：
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141010 0:02:48 [ERROR] Slave I/O: error connecting to master \'my@172.17.210.199:3306\' - retry-time: 60 retries: 1, Error_code: 2003
141010 0:03:48 [ERROR] Slave I/O: error connecting to master \'my@172.17.210.199:3306\' - retry-time: 60 retries: 2, Error_code: 2003
141010 0:04:48 [ERROR] Slave I/O: error connecting to master \'my@172.17.210.199:3306\' - retry-time: 60 retries: 3, Error_code: 2003
141010 0:05:48 [ERROR] Slave I/O: error connecting to master \'my@172.17.210.199:3306\' - retry-time: 60 retries: 4, Error_code: 2003
141010 0:06:48 [ERROR] Slave I/O: error connecting to master \'my@172.17.210.199:3306\' - retry-time: 60 retries: 5, Error_code: 2003
141010 0:07:48 [ERROR] Slave I/O: error connecting to master \'my@172.17.210.199:3306\' - retry-time: 60 retries: 6, Error_code: 2003
解决方法： 
 
导致lave_IO_Running 为connecting 的原因主要有以下 3 个方面： 
 
1、网络不通 
2、密码不对 
3、pos不对
解决步骤：
1、对于第一个问题，一般情况下都是可以排除的，也是最容易排除的。
2、在主库上修改用来复制的用户的密码。
3、 在做chang to 的时候注意log_pos 是否跟此时主机的一样。在主机上 show master status \G ;可以查看到
mysql> show master status \G;
*************************** 1. row ***************************
             File: masters-bin.000003
         Position: 2392
     Binlog_Do_DB:
Binlog_Ignore_DB:
Executed_Gtid_Set:
1 row in set (0.00 sec)
ERROR:
No query specified
从机上面执行change to 的正确
CHANGE MASTER TO
MASTER_HOST='172.17.210.199',
MASTER_USER='my',
MASTER_PASSWORD='123456',
MASTER_LOG_FILE='masters-bin.000003',
MASTER_LOG_POS= 2392;

我的问题，就是主机的防火墙没有关闭


====================================================================
由于主服务器异外重启, 导致从报错, 错误如下:
show slave status错误:
mysql> show slave status\G
Master_Log_File: mysql-bin.000288
Read_Master_Log_Pos: 627806304
Relay_Log_File: mysql-relay-bin.000990
Relay_Log_Pos: 627806457
Relay_Master_Log_File: mysql-bin.000288
Slave_IO_Running: No
Slave_SQL_Running: Yes
Exec_Master_Log_Pos: 627806304
Relay_Log_Space: 627806663


......
Last_IO_Error: Got fatal error 1236 from master when  reading data from binary log:
'Client requested master to start  replication from impossible position'
mysql错误日志:

tail /data/mysql/mysql-error.log
111010 17:35:49 [ERROR] Error reading packet from server: Client requested master
to start replication from impossible position ( server_errno=1236)
111010 17:35:49 [ERROR] Slave I/O: Got fatal error 1236 from master when reading data
from binary log: 'Client requested master to start replication from impossible
position', Error_code: 1236
111010 17:35:49 [Note] Slave I/O thread exiting, read up to log 'mysql-bin.000288',
position 627806304
按照习惯, 先尝试必改position位置.

mysql> stop slave;
mysql> change master to master_log_file='mysql-bin.000288',master_log_pos=627625751;
mysql> start slave;
错误依旧, 接下来登陆到主服务器查看binlog日志.
先按照错误点的标记去主服务器日志中查找:

[root@db1 ~]# mysqlbinlog --start-position=627655136 /data/mysql/binlog/mysql-bin.000288
/*!40019 SET @@session.max_insert_delayed_threads=0*/;
/*!50003 SET @OLD_COMPLETION_TYPE=@@COMPLETION_TYPE,COMPLETION_TYPE=0*/;
DELIMITER /*!*/;
# at 4
#111010 13:31:19 server id 4 end_log_pos 106 Start: binlog v 4, server v 5.1.45-log
created 111010 13:31:19
# Warning: this binlog is either in use or was not closed properly.
BINLOG '
F1aTTg8EAAAAZgAAAGoAAAABAAQANS4xLjQ1LWxvZwAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA
AAAAAAAAAAAAAAAAAAAAAAAAEzgNAAgAEgAEBAQEEgAAUwAEGggAAAAICAgC
'/*!*/;
DELIMITER ;
# End of log file
ROLLBACK /* added by mysqlbinlog */;
/*!50003 SET COMPLETION_TYPE=@OLD_COMPLETION_TYPE*/;
没有看到这个位置.

[root@db1 ~]# mysqlbinlog /data/mysql/binlog/mysql-bin.000288 > test.txt

less text.txt
看最后一部分
# at 627625495
#111010 16:35:46 server id 1 end_log_pos 627625631 Query thread_id=45613333
exec_time=32758 error_code=0
SET TIMESTAMP=1318289746/*!*/;
delete from freeshipping_bef_update where part='AR-4006WLM' and code=''
/*!*/;
# at 627625631
#111010 16:35:46 server id 1 end_log_pos 627625751 Query thread_id=45613333
exec_time=32758 error_code=0
SET TIMESTAMP=1318289746/*!*/;
delete from shippingFee_special where part='AR-4006WLM'
/*!*/;
DELIMITER ;
# End of log file
ROLLBACK /* added by mysqlbinlog */;
/*!50003 SET COMPLETION_TYPE=@OLD_COMPLETION_TYPE*/;
找到最接近错误标记627655136的一个position是627625631.

再回到slave机器上change master, 将postion指向这个位置.

mysql> stop slave;
Query OK, 0 rows affected (0.00 sec)

mysql> change master to master_log_file='mysql-bin.000288',master_log_pos=627625631;
Query OK, 0 rows affected (0.06 sec)

mysql> start slave;
Query OK, 0 rows affected (0.00 sec)
再次查看

mysql> show slave status\G
*************************** 1. row ***************************
Slave_IO_State: Queueing master event to the relay log
Master_Host: 192.168.21.105
Master_User: rep
Master_Port: 3306
Connect_Retry: 10
Master_Log_File: mysql-bin.000289
Read_Master_Log_Pos: 25433767
Relay_Log_File: mysql-relay-bin.000003
Relay_Log_Pos: 630
Relay_Master_Log_File: mysql-bin.000289
Slave_IO_Running: Yes
Slave_SQL_Running: Yes
主从同步正常了, 同样的方法修复其它slave机器.