title: what number and/or kind of dynos pick in heroku
body: <p>I'm new in heroku and I wonder what questions should ask to myself to pick a save configuration(number and kind) of dynos in heroku.</p>
  
  <p>If I have a chat like <a href="https://devcenter.heroku.com/articles/python-websockets" rel="nofollow">this</a> made in python, gunicorn, redis and websockets to 800 concurrent users. The lifetime of this chat will last few hours(close to 5 hours) and finally when the chat is no longer used I want to recover the last message of each user.</p>
  
  <p>I'm planning take one PX but I'm afraid the system could fail and loose all due to redis save all in RAM so maybe should I take three 3X? or maybe two PX?</p>
  
  <p>And what about redis, <a href="https://addons.heroku.com/rediscloud" rel="nofollow">this</a> is the available plans.</p>
  
  <p>Should I use nginx? I think is not necesary, there is almost 90% static pages.</p>
  
  <p>More details:
  The info sent in websockets are json with a lenght of 100 tops.</p>