Hi

As we are using Cassandra 1.2.11 and we will want to move to 2.1 as soon as it will be released and considered stable enough, we will have to make a few migrations :

1.2.11   --> 1.2.last (16 currently)
1.2.last -->  2.0.last
2.0.last -->  2.1.last

The point is we ran into a lot of migrations since we started (C* 0.7 --> 0.8 --> 1.0 --> 1.1 --> 1.2). Not even one of our migration went totally well. Even if we never lost any data, which is a very important thing, we never upgraded Cassandra smoothly either. We are supposed to be able to do it through a rolling restart. We never could. We always ran into errors and ended restarting the whole cluster.

I supposed we are not the only ones in this case since I remember a Spotify conference "How not to use Cassandra" were they expressed the same kind of problems.

My question is quite simple:

Since we use AWS EC2 instances, Is it possible to upgrade Cassandra through a new DC as it is recommended while switching to vnodes ?

(http://www.datastax.com/documentation/cassandra/1.2/cassandra/configuration/configVnodesProduction_t.html)

I think that if it is possible, we would make the first minor upgrade through rolling restart (those one are generally smooth enough) and the 2 major upgrades through "DC migrations".

Alain