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From Jean-Daniel Cryans <jdcry...@apache.org>
Subject Re: Replication terminology "master-master"
Date Tue, 25 Nov 2014 16:09:06 GMT
On Mon, Nov 24, 2014 at 8:29 PM, lars hofhansl <larsh@apache.org> wrote:

> Hmm... From that angle all we really have is master-slave replication,
> without limit as how it can be setup.A master can be slave too, and a slave
> a master, and cycles are allowed.
> I find "cyclical replication" more confusing than "master-master"
> (although it's true that master-master is strictly a subset of cyclical -
> just a cycle of two).

I agree with that.

> We might want to scrap all the terms and just state (hopefully a bit
> nicer) what I tried to say in the first two sentences above.

One thing about "master-master" is that some audiences will get it right
away, for example folks coming from the MySQL world, but maybe we want to
skip using it in our doc and just say what you wrote above "A master can be
slave too, and a slave a master, and cycles are allowed" since with just
that you can build everything else.

> -- Lars
>       From: Misty Stanley-Jones <mstanleyjones@cloudera.com>
>  To: dev@hbase.apache.org
>  Sent: Monday, November 24, 2014 7:26 PM
>  Subject: Replication terminology "master-master"
> Hi all,
> I think "master-master" is a term that should be re-thought. It is not
> really a "type" of replication, but refers to a characteristic of  a
> cluster, specifically a cluster which participates in multiple clusters
> with different roles -- it is a slave in one cluster and a master in
> another cluster. I think with the current terminology, people confuse it
> with "cyclical" replication, in which two clusters replicate to each other,
> and eventually each has all the data from both.
> Since master-master in this sense is really not a type of replication, I
> think we should just scrap it. You can have master-slave replication or
> cyclical replication, or a combination. With master-slave replication, a
> cluster can fulfill both roles at the same time, as long as it is in
> different clusters. This is easy to understand as a sort of recursive
> cascade.
> Am I explaining it right, and what do you guys think about changing our
> terminology?
> Thanks,
> Misty

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