Asp默认的上传文件大小限制是200K

默认情况下，使用Server.CreateObject("Scripting.FileSystemObject") 对象去上传文件超过默认的大小限制后，相关的文件后缀将会是个空，大小也会是0

如如何修改默认设置参考 http://www.banmanpro.com/support2/File_Upload_limits.asp

 以下部分引用原文：

When trying to upload files over 200KB on IIS 6 the file may never upload and you either get an error or are sent to a blank screen.  By default Windows 2003 server limits file uploads to about 200KB in size.  To overcome this limit you must edit the IIS metabase.xml file.

1. Before you can edit the metabase.xml file you must tell IIS to allow you to edit the file.  In IIS, right click the name of the server and select properties.  Check "Enable Direct Metabase Edit".
   
   
2. Find the metabase.xml file located in C:\windows\sytem32\inetserv and open the file in Notepad.
3. Search for AspMaxRequestEntityAllowed and increase the value.  The default value is 204800 (200K).  Setting the value to 1000000 will allow 1 MB file uploads.
4. You may now wish to uncheck the IIS property called "Enable Direct Metabase Edit".

To increase the file download size limit, repeat all steps above but in Step 3 find the parameter calledAspBufferingLimit.  The default download limit is 4MB.