Be aware that at RF 2 the Quorum is 2, so you cannot afford to lose a replica when working at Quorum. 3 is really the starting point if you want some redundancy.
If you want to get your data offsite how about doing snapshots and moving them off site http://wiki.apache.org/cassandra/Operations#Consistent_backups The guide from Data Stax will give you a warm failover site, which sounds a bit more than what you need. Hope that helps. Aaron On 28 Mar 2011, at 22:47, Brian Lycett wrote: > Hello. > > I'm setting up a cluster that has three nodes in our production rack. > My intention is to have a replication factor of two for this. > For disaster recovery purposes, I need to have another node (or two?) > off-site. > > The off-site node is entirely for the purpose of having an offsite > backup of the data - no clients will connect to it. > > My question is, is it possible to configure Cassandra so that the > offsite node will have a full copy of the data set? > That is, somehow guarantee that a replica of all data will be written to > it, but without having to resort to an ALL consistency level for writes? > Although the offsite node will on a 20Mbit leased line, I'd rather not > have the risk that the link goes down and breaks the cluster. > > I've seen this suggestion here: > http://www.datastax.com/docs/0.7/operations/datacenter#disaster > but that configuration is vulnerable to the link breaking, and uses four > nodes in the offsite location. > > > Regards, > > Brian > >
