title: Whats the difference between Paxos and W+R>=N in Cassandra?
body: <p>Dynamo-like databases (e.g. Cassandra) can enforce consistency by means of quorum, i.e. a number of synchronously written replicas (W) and a number of replicas to read (R) should be chosen in such a way that W+R>N where N is a replication factor. On the other hand, PAXOS-based systems like Zookeeper are also used as a consistent fault-tolerant storage.</p>
  
  <p>What is the difference between these two approaches? Does PAXOS provide guarantees that are not provided by W+R>N schema?  </p>