The current setup for upload space directory structure is really bad.
First there is the 32000 limit to the number of subfolders in linux that makes it a complex task to host more than 32000 blogs off one server.
Second, and more important, is the problem that the directories are named after the blogid. This means the requests to any uploaded images must go through a php script, SQL queries, etc., making it really more performance consuming for the server. it also makes it virtually impossible to serve images off a lightweight http server without heavy modifications to the script. Why oh why not use the blog name as the directory name ? If it works for URLs it should work for file systems, and it would allow to mod_rewrite the url and serve directly static files from another web server, and without php/sql.
