I response to my previous post, here is the basics of a sharded cluster MongoDB setup. As you can see, if you were to place each element on its own server you’d end up with alot of servers.
After a bit of research into how each mongo element is used and its performance characteristics, I arrived at the following sleek(er) configuration of servers. This is arrangement is symmetric to allow for cross data center architectures.
This post was heavily influenced by a concise Will Burton post: http://two4seven.me/sharding/