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Date: Tue, 25 Nov 2014 04:29:33 +0000 (UTC)
From: lars hofhansl <larsh@apache.org>
Reply-To: lars hofhansl <larsh@apache.org>
To: "dev@hbase.apache.org" <dev@hbase.apache.org>
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Subject: Re: Replication terminology "master-master"
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Hmm... From that angle all we really have is master-slave replication, with=
out limit as how it can be setup.A master can be slave too, and a slave a m=
aster, 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 cyc=
le of two).
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.
-- Lars

      From: Misty Stanley-Jones <mstanleyjones@cloudera.com>
 To: dev@hbase.apache.org=20
 Sent: Monday, November 24, 2014 7:26 PM
 Subject: Replication terminology "master-master"
  =20
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=C2=A0 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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