Thanks Rob, this makes sense. We only have one rack at this point, so I think it'd be better to start with PropertyFileSnitch to make Cassandra think that these nodes each are in a different rack without having to put them on different subnets. And I will have more flexibility (at the cost of keeping the property file in sync) when it comes to growth. What do you think?
-- Drew On Nov 5, 2012, at 7:50 PM, Rob Coli <rc...@palominodb.com> wrote: > On Mon, Nov 5, 2012 at 12:23 PM, Drew Kutcharian <d...@venarc.com> wrote: >>> Switching from SimpleStrategy to RackAware can be a pain. >> >> Can you elaborate a bit? What would be the pain point? > > If you don't maintain the same replica placement vis a vis nodes on > your cluster, you have to dump and reload. > > Simple example, 6 node cluster RF=3 : > > SimpleSnitch : A B C D E F > > Data for natural range of A is also on B and C, the "next" nodes in the ring. > > RackAwareSnitches : A B C D E F > "racks" they are in : 1 1 2 2 3 3 > > Data for natural range of A is also on C and E, because despite not > being the next nodes in the RING, they are the first nodes in the next > rack. > > If however you go from simple to rack aware and put your nodes in racks like : > > A B C D E F > 1 2 3 1 2 3 > > Then you have the same replica placement that SimpleStrategy gives you > and can safely switch strategies/snitches on an existing cluster. Data > for A is on B and C, on the same hosts, but for different reasons. Use > nodetool getendpoints to test. > > =Rob > > -- > =Robert Coli > AIM>ALK - rc...@palominodb.com > YAHOO - rcoli.palominob > SKYPE - rcoli_palominodb
