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From Drew Kutcharian <d...@venarc.com>
Subject Re: Single Node Cassandra Installation
Date Sun, 11 Nov 2012 02:16:24 GMT
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 <rcoli@palominodb.com> wrote:

> On Mon, Nov 5, 2012 at 12:23 PM, Drew Kutcharian <drew@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&GTALK - rcoli@palominodb.com
> YAHOO - rcoli.palominob
> SKYPE - rcoli_palominodb


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