title: When does Cassandra hit Amdahl's law?
body: <p>I am trying to understand the claims that Cassandra scales linearly with the number of nodes.  In a quick look around the 'net I have not seen much of a treatment of this topic.  Surely there are serial processing elements in Cassandra that must limit the speed gained as N increases.  Any thoughts, pointers or links on this subject would be appreciated.</p>
  
  <p>Edit to provide perspective:<br>
  I am working on a project that has a current request for a 1,000+ node Cassandra infrastructure.  I did not come-up with this spec.  I find myself proposing that N be reduced to a range between 200 and 500, with each node being at least twice as fast for serial computation.  This is easy to achieve without a cost penalty per node by making simple changes to the server configuration.</p>