We are using Cassandra 1.2.11 on AWS EC2 services.

I read that we can use different A-Z to be more "crash tolerant". Basically, using a RF=3 and placing servers into different zones like node1-zoneA node2-zoneB node3-zoneC node4-zoneA... As replicas are placed to the next server in the ring we can manage to have a replica in each zone and for each replica. So all the data is present in the 3 zones (A, B and C).

Is there a way to achieve this exact same result using vnodes ? Would it be possible, using EC2Snitch (or EC2MultiRegionSnitch) and vnodes, to make sure to spread replicas among available A-Z automatically ?

I know that a second DC would help recovering from a zone outage, but, the cost is not the same.