title: Is it necessary for memcached to replicate its data?
body: <p>I understand that memcached is a distributed caching system. However, is it entirely necessary for memcached to replicate? The objective is to persist sessions in a clustered environment.</p>
  
  <p>For example if we have memcached running on say 2 servers, both with data on it, and server #1 goes down, could we potentially lose session data that was stored on it? In other words, what should we expect to see happen should any memcached server (storing data) goes down and how would it affect our sessions in a clustered environment?</p>
  
  <p>At the end of the day, will it be up to use to add some fault tolerance to our application? For example, if the key doesn't exist possibly because one of the servers it was on went down, re-query and store back to memcached?</p>
  
  <p>From what I'm reading, it appears to lean in this direction but would like confirmation: <a href="https://developers.google.com/appengine/articles/scaling/memcache#transient" rel="nofollow">https://developers.google.com/appengine/articles/scaling/memcache#transient</a></p>
  
  <p>Thanks in advance!</p>