title: PHP: memcache and memcached - addServer question
body: <p>Using PHP's <a href="http://php.net/manual/en/book.memcache.php" rel="nofollow">memcache</a> and <a href="http://php.net/manual/en/book.memcached.php" rel="nofollow">memcached</a>  Both of them have addServer.</p>
  
  <p>So I add 2 different memcache servers running on different hardware and even on different ports.
  When I "set", "add" or "increment" -- which one will be choosen with memcache and which one with memcached? If one of the servers becomes unavailable, and then become available again, what happens?</p>
  
  <p>And how do I turn on redunandancy/replication of data on both?</p>
  
  <p>Say I want data to be stored both to server A and server B, and when one is unavailble, and then available again it gets back to whats on other server.</p>
  
  <p>I think this can be done with memcache cluster, but how PHP's client libs memcache and memcached are handling that?</p>