I've had a 3-node hardware Riak cluster lying around for about 4 months now, but only just today cut over from Postgres to it. I can talk to you about how shiny Riak is on day 1, but as this presentation shows, the day 1 behavior of a Riak cluster can be a bit of a trap.

Great to hear that you're cutting over to Riak. We highly recommend that your minimum cluster size is your N value (replication value) + 2. I your case that likely means 5 nodes for your starting cluster, not 3. There are many reasons. http://basho.com/blog/technical/2012/04/27/Why-Your-Riak-Clu...

Obviously great to know. Thanks!

Thomas, I'm in the middle of evaluating document stores and am perhaps getting stars in my eyes from Riak's easy-to-scale story. I'd love to hear more about your experiences once your cluster has had time to marinate a bit.