We are setting up my application around Cassandra .8.0 (will move to Cassandra 1.0 in the near future). In production the application will be running in a two (or more) node cluster with RF 2. In development, we do not always have 2 machines to test on, so we may have to run a Cassandra cluster consisting of only a single node. In this case, we have to reduce the RF of the column family to 1. We may need to switch machines from one schema to the other and back again. This is not something that will occur often and not in live production. I noticed that there is an alter keyspace command in the cassandra-cli and PyCassa, which should allow me to change the strategy options. So, it is possible to switch a Cassandra instance from RF 1 to RF 2 and back again? Will we have something horrible happen if we try to do it on a node with data? Is there anything in particular that we have to do before/after the transition to make the transition safe?
I assume that we have to first alter the keyspace and then decommission one of the nodes and this will prevent us from losing half of our data.
