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From Oleksandr Shulgin <oleksandr.shul...@zalando.de>
Subject Re: New token allocation and adding a new DC
Date Tue, 16 Jan 2018 16:02:30 GMT
On Tue, Jan 16, 2018 at 4:16 PM, Alexander Dejanovski <
alex@thelastpickle.com> wrote:

> Hi Oleksandr,
>
> if bootstrap is disabled, it will only skip the streaming phase but will
> still go through token allocation and thus should use the new algorithm.
> The algorithm won't try to spread data based on size on disk but it will
> try to spread token ownership as evenly as possible.
>
> The problem you'll run into is that ownership for a specific keyspace will
> be null as long as the replication strategy isn't updated to create
> replicas on the new DC.
> Quickly thinking would make me do the following :
>
>    - Create enough nodes in the new DC to match the target replication
>    factor
>    - Alter the replication strategy to add the target number of replicas
>    in the new DC (they will start getting writes, and hopefully you've already
>    segregated reads)
>    - Continue adding nodes in the new DC (with auto_bootstrap = false),
>    specifying the right keyspace to optimize token allocations
>    - Run rebuild on all nodes in the new DC
>
> I honestly never used it but that's my understanding of how it should work.
>

Oh, that's neat.  We will try this and see if it helps.

Thank you!
--
Alex

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