Your options (if you are going to do it yourself and not use S3 or cachefly): 1. rsync on the backend; it's easy, it's relatively fast, but it is asynchronous

Your options (if you are going to do it yourself and not use S3 or cachefly): 1. rsync on the backend; it's easy, it's relatively fast, but it is asynchronous and files won't be immediately available on all servers. 2. An inotify watcher that copies files to the slaves when a file is written or changed on the master. Faster than an rsync solution, but you'll need to write it yourself. In either case you will want to seriously question whether you should do it yourself, look at the costs for keeping machines operational and how much you are paying for bandwidth.