When using RESPONSE.write to output data(Such as Data Stream in Wendelin), since an output stream is stored in a tempfile, if a downloading stream is larger than zope server's available diskspace, disk full io error occurs and download fails. To solve the problem, create a tempfile every about 1 GB of the stream and delete each file once its data is downloaded. Then, if client's download speed is fast enough, ZServer should not need to create a lot of tempfiles, it should be able to handle a stream that is larger than available disk space.