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From Eric tamme <eta...@gmail.com>
Subject Re: Replica data distributing between racks
Date Mon, 02 May 2011 19:30:30 GMT
On Mon, May 2, 2011 at 3:22 PM, Jonathan Ellis <jbellis@gmail.com> wrote:
> On Mon, May 2, 2011 at 2:18 PM, aaron morton <aaron@thelastpickle.com> wrote:
>> When the NTS selects replicas in a DC it orders the tokens available in  the DC,
then (in the first pass) iterates through them placing a replica in each unique rack.  e.g.
if the RF in each DC was 2, the replicas would be put on 2 unique racks if possible. So the
lowest token in the DC will *always* get a write.
>
> It's supposed to start w/ the node closest to the token in each DC, so
> that shouldn't be the case unless you are using BOP/OPP instead of RP.
>

I am using a RandomPartitioner as shown below:

Cluster Information:
   Snitch: org.apache.cassandra.locator.PropertyFileSnitch
   Partitioner: org.apache.cassandra.dht.RandomPartitioner

So as far as "closeness" .. how does that get factored in when using a
PropertyFileSnitch?  Is one rack closer than the other?  In reality
for each data center there are two nodes in the same rack on the same
switch,  but I set the topology file up to have 2 racks per data
center specifically so I would get distribution.

-Eric

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