I know these questions are hard to answer :) But I want to get some kind of an idea of the impact of separating services onto different servers.
Specifically, I am setting up a website that will have a media server (apache serving static files), a app server (apache processing php files), a master db server and a slave db server.
I was going to run memcached on both the media and app servers as a shared pool, but was wondering if it was expensive (in terms of time and resources) to do so? Obviously everytime a memcached call is requested (from the app server) it has to make a tcp connection to the media server, work out where the results are and then return them.
For a small website setup like this, would it be better to bump up the ram on the app server and NOT pool memcached across servers? Or is the difference so small its not worth worrying about?
Even though I used memcached as the example, I would prefer if answers are kept fairly generic as the same scenario could be applied to other services (like a db).