title: Hybrid P2P's server data directory
body: <p>I'm developing a some sort like P2P system here.
  The types of P2P network that I'm going to use is Hybrid P2P.
  But, there's a problem here which I don't know how to solve. 
  It's the data directory.
  How does the data directory works?
  How does it knows that which nodes contain what files?</p>