We've got a relatively low-traffic site (~1K pageviews/day) hosted on a single server, and expect it to grow significantly over the next few years. I'm thinking of moving over to Rackspace CloudServer or EC2 and firing up 3 nodes (all on CentOS): 2 x Web (Apache) - with loadbalancer 1 x MySQL (for the Wordpress powered part) The question is where to put Cassandra right now... Should it sit on each Web node, or the MySQL node? My thought right now is to put it on Web nodes. It's my understanding that Cassandra has the benefits of fault-tolerance (i.e. if we take a node down, the site is still operational). So even with only 2 nodes, we'd have that benefit as opposed to just putting it on the MySQL node. Also, as we scale up and add another node, a cassandra instance can come along with it and the php can always run its queries on localhost. Is this a good idea?