什么是将文件传输到其他服务器的最佳方法？

Im running a file host thats grown beyond the capacity of a single server, and I need to implement multiple server storage of files. I'd like to do this as cheap as possible, so those fancy mass storage methods are out of the question. I simply want to move a file thats uploaded by the user to the "gateway" server, which hosts all the http and mysql, to one of the media servers. It can either be done at the end of the user's request, or via cron every couple of minutes. Im running a file host thats grown beyond the c