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From Andrey Ilinykh <ailin...@gmail.com>
Subject Re: Clarification on how multi-DC replication works
Date Tue, 11 Feb 2014 18:25:33 GMT
On Tue, Feb 11, 2014 at 10:14 AM, Mullen, Robert
<robert.mullen@pearson.com>wrote:

> Thanks for the feedback.
>
> The picture shows a sample request, which is why the coordinator points to
> two specific nodes.  What I was trying to convey that the coordinator node
> would ensure that 2 of the 3 nodes were written to before reporting success
> to the client.
>
This is my point. ANY 2 of 3. Your picture shows specific 2 of 3.



>
> I found the article here, it says that the non-blocking writes to the 2nd
> data center are asynchronous.  Is this blog post incorrect as well?
>
> http://www.datastax.com/dev/blog/deploying-cassandra-across-multiple-data-centers
>

Why is it incorrect? Everything is asynchronous, both local and remote. The
coordinator simply waits for response from local nodes. But it doesn't make
it synchronous, because it waits for response from ANY 2 nodes.

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