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From Misty Stanley-Jones <mstanleyjo...@cloudera.com>
Subject Re: Replication terminology "master-master"
Date Fri, 28 Nov 2014 01:16:14 GMT
I think of multi-master more in the case of load-balancing, where multiple
machines are all fulfilling the role of master at the same time on the same
cluster. I can't picture how it would apply to multiple clusters. I'm not
sure, maybe i'm not getting it, but multi-master seems like a subtlely
different thing.

On Thu, Nov 27, 2014 at 1:23 AM, Nick Dimiduk <ndimiduk@gmail.com> wrote:

> I guess "multi-master" is the more common term for this kind of
> replication.
>
> On Tue, Nov 25, 2014 at 11:05 AM, Demai Ni <nidmgg@gmail.com> wrote:
>
> > Agree with you guys. I also experienced difficulty to explain about
> > Master-Master and  cyclical to my users before, until I began to talk
> about
> > M-S only as building-block, which can be applied as one please.
> >
> > Just like to chime in another point, maybe the document should emphasize
> > that the Master or Slave term is from *the perspective of
> > 'table:columnFamly'*. It is often confused when using term as
> > 'Master-cluster' or 'Slave-Cluster' as if the cluster as a whole is a
> > Master/Slave. Unless the clusters are setup strictly as one-way
> > replication. the Cluster often serves for both roles.
> >
> > Demai
> >
> > On Tue, Nov 25, 2014 at 9:21 AM, Andrew Purtell <
> andrew.purtell@gmail.com>
> > wrote:
> >
> > >
> > > > On Nov 25, 2014, at 11:09 AM, Jean-Daniel Cryans <
> jdcryans@apache.org>
> > > wrote:
> > > >
> > > > "A master can be
> > > > slave too, and a slave a master, and cycles are allowed" since with
> > just
> > > > that you can build everything else.
> > >
> > > +1
> > >
> > >
> > >
> > > > On Nov 25, 2014, at 11:09 AM, Jean-Daniel Cryans <
> jdcryans@apache.org>
> > > wrote:
> > > >
> > > >> 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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