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From Tyler Hobbs <ty...@datastax.com>
Subject Re: NetworkTopologyStrategy and nodes ?
Date Thu, 17 Oct 2013 15:55:10 GMT
On Sat, Oct 12, 2013 at 9:08 AM, Andrew Cobley <a.e.cobley@dundee.ac.uk>wrote:

>
>  "In the following graphic, notice the tokens are assigned to alternating
> racks. For more information, see *Generating Tokens*<http://www.datastax.com/docs/1.1/initialize/token_generation#token-gen-cassandra>
> ."
>
>  Seems to imply that the strategy relies on placing tokens on different
> racks which won't happen with nodes ?
>

Right, you won't be able to control whether neighboring tokens have
alternating racks with vnodes.

The main reason that they should be alternating without vnodes is to avoid
a large imbalance in ring ownership.  Without vnodes, if a node owns just
one extra range, it will make a big difference because each range is quite
large.

With vnodes, this is much less of a concern.  You still have a lot of
"imbalances", but they are each fairly small and in aggregate they mostly
cancel each other out.

-- 
Tyler Hobbs
DataStax <http://datastax.com/>

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