On Fri, Jun 4, 2010 at 11:14 AM, Philip Stanhope <pstanh...@wimba.com> wrote: > I guess I'm thick ... > > What would be the right choice? Our data demands have already been proven to > scale beyond what RDB can handle for our purposes. We are quite pleased with > Cassandra read/write/scale out. Just trying to understand the operational > considerations. >
Cassandra supports online topology changes, but those operations are not cheap. If you are expecting frequent addition and removal of nodes from a ring, things will be very unstable or slow (or both). As I already mentioned, having a large cluster (and 40 nodes qualifies right now) with RF=number of nodes is going to make read and write operations get more and more expensive as the cluster grows. While you might see reasonable performance at current, small scale, it will not be the case when the cluster gets large. I am not aware of anything like Cassandra (or any other Dynamo system) that support such extensive replication and topology churn. You might have to write it. b
