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From aaron morton <aa...@thelastpickle.com>
Subject Re: Docs: Token Selection
Date Fri, 17 Jun 2011 03:45:27 GMT
> But, I'm thinking about using OldNetworkTopStrat. 

NetworkTopologyStrategy is where it's at. 

A
-----------------
Aaron Morton
Freelance Cassandra Developer
@aaronmorton
http://www.thelastpickle.com

On 17 Jun 2011, at 01:39, AJ wrote:

> Thanks Eric!  I've finally got it!  I feel like I've just been initiated or something
by discovering this "secret".  I kid!
> 
> But, I'm thinking about using OldNetworkTopStrat.  Do you, or anyone else, know if the
same rules for token assignment applies to ONTS?
> 
> 
> On 6/16/2011 7:21 AM, Eric tamme wrote:
>> AJ,
>> 
>> sorry I seemed to miss the original email on this thread.  As Aaron
>> said, when computing tokens for multiple data centers, you should
>> compute them independently for each data center - as if it were its
>> own Cassandra cluster.
>> 
>> You can have "overlapping" token ranges between multiple data centers,
>> but no two nodes can have the same token, so for subsequent data
>> centers I just increment the tokens.
>> 
>> For two data centers with two nodes each using RandomPartitioner
>> calculate the tokens for the first DC normally, but int he second data
>> center, increment the tokens by one.
>> 
>> In DC 1
>> node 1 = 0
>> node 2 = 85070591730234615865843651857942052864
>> 
>> In DC 2
>> node 1 = 1
>> node 2 =  85070591730234615865843651857942052865
>> 
>> For RowMutations this will give each data center a local set of nodes
>> that it can write to for complete coverage of the entire token space.
>> If you are using NetworkTopologyStrategy for replication, it will give
>> an offset mirror replication between the two data centers so that your
>> replicas will not get pinned to a node in the remote DC.  There are
>> other ways to select the tokens, but the increment method is the
>> simplest to manage and continue to grow with.
>> 
>> Hope that helps.
>> 
>> -Eric
>> 
> 


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