If you have 3 nodes of RF=3, you can continue the service on cassandra even if one of the node will fail ( by hardware or software failure ). One other benefit is you can shutdown one node for maintenance or patch up without service interruption.
If you run your service with 2 node and RF=2, your data will be replicated but your service will not be redundant. ( You can't stop both of nodes ) 2012/2/29 Ertio Lew <ertio...@gmail.com>: > @Aaron: Are you suggesting 3 nodes (rather than 2) to allow quorum > operations even at the temporary loss of 1 node from cluster's reach ? I > understand this but I just another question popped up in my mind, probably > since I'm not much experienced managing cassandra, so I'm unaware whether it > may be a usual case that some out of n nodes of my cluster may be > down/unresponsive or out of cluster reach? (I, actually, considered this > situation like exceptional circumstance not normal one !?) > > > On Tue, Feb 28, 2012 at 2:34 AM, aaron morton <aa...@thelastpickle.com> > wrote: >> >> 1. I am wandering what is the minimum recommended cluster size to start >> with? >> >> IMHO 3 >> http://thelastpickle.com/2011/06/13/Down-For-Me/ >> >> A >> >> ----------------- >> Aaron Morton >> Freelance Developer >> @aaronmorton >> http://www.thelastpickle.com >> >> On 28/02/2012, at 8:17 AM, Ertio Lew wrote: >> >> Hi >> >> I'm creating an networking site using cassandra. I am wanting to host this >> application but initially with the lowest possible resources & then slowly >> increasing the resources as per the service's demand & need. >> >> 1. I am wandering what is the minimum recommended cluster size to start >> with? >> Are there any issues if I start with as little as 2 nodes in the cluster? >> In that case I guess would have replication factor of 2. >> (this way I would require at min. 3 vps, 1 as web server & the 2 for >> cassandra cluster, right?) >> >> 2. Anyone using cassandra with such minimal resources in >> production environments ? Any experiences or difficulties encountered ? >> >> 3. In case, you would like to recommend some hosting service suitable for >> me ? or if you would like to suggest some other ways to minimize the >> resources (actually the hosting expenses). >> >> > -- maki
