mysql数据库实现主从同步是的错误问题：
主从同步不了；但是参数设置Slave_IO_Running: Yes， Slave_SQL_Running: Yes主从一致的。
查看从日志显示如下错误信息：
111201 17:29:13 [ERROR] Error reading packet from server: Lost connection to MySQL server during query ( server_errno=2013) 111201 17:29:13 [Note] Slave I/O thread: Failed reading log event, reconnecting to retry, log 'mysql-bin.000048' position 432318024 111201 17:29:13 [Note] Slave: connected to master 'emuser@221.10.1.60:3306',replication resumed in log 'mysql-bin.000048' at position 432318024 111202 20:19:20 [ERROR] Slave: Error 'Column 'refresh' cannot be null' on query. Default database: 'cdn_view'. Query: 'insert into DNS_ALL values (NULL,'eqifa.com','pvyigao','A','210.51.100.11',360,'CNC',NULL,NULL,NULL,NULL,NULL,'2014092000','root.eqifa.com.','ns.esoso.com.',0)', Error_code: 1048 111202 20:19:20 [ERROR] Error running query, slave SQL thread aborted. Fix the problem, and restart the slave SQL thread with "SLAVE START". We stopped at log 'mysql-bin.000049' position 263269149 111209 9:32:41 [Note] /usr/libexec/mysqld: Normal shutdown
解决方法：
从日志上看可能是插入数据，从的没有正常同步；或者主的插入记录错误。
首先在从上slave stop;然后slave start；问题依旧
最后按照笨方法重新做了下；最终还是解决问题了。
操作步骤如下：
1、从停止复制，主锁表
slave stop; flush tables with read lock;
记录主的Position
2、rsync库文件到从
3、从手动执行同步
change master to master_host='123.57.47.16=54',master_user='emuser',master_password='emaradmin', master_log_file='mysql-bin.000056', master_log_pos=323979991;
4、启动从复制
slave start
5、主解锁
unlock tables;
6、主插入记录；查看从是否有新记录。
