title: Scalability issues with server based authentication
body: <p>I was reading up on problems with server based authentication. I need help with elaboration on the following point.</p>
  
  <blockquote>
    <p>Scalability: Since sessions are stored in memory, this provides problems with scalability. As our cloud providers start replicating servers to handle application load, having vital information in session memory will limit our ability to scale.</p>
  </blockquote>
  
  <p>I don't seem to understand why "... having vital information in session memory will limit our ability to scale", will limit the ability to scale. Is it just because the information is being replicated.. so it's to do with redundancy? I don't think so. Anyway, would anyone be kind enough to explain this further? Much appreciated.</p>