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Date: Wed, 10 Dec 2014 11:02:46 +0100
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Subject: Re: Replication terminology "master-master"
From: Lars George <lars.george@gmail.com>
To: "dev@hbase.apache.org" <dev@hbase.apache.org>
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+1 :)

On Wed, Dec 10, 2014 at 5:36 AM, Nick Dimiduk <ndimiduk@gmail.com> wrote:

> I suggest we drop the lingo and just say what we mean explicitly: "A
> cluster may act as both a replication source and destination
> simultaneously."
>
> On Tuesday, December 9, 2014, Misty Stanley-Jones <
> mstanleyjones@cloudera.com> wrote:
>
> > Can I get some consensus on what we should be saying about different
> > replication types? It's a bit over my head and I don't feel comfortable
> > making a unilateral decision.
> >
> > On Sun, Nov 30, 2014 at 8:40 AM, Michael Segel <
> michael_segel@hotmail.com
> > <javascript:;>>
> > wrote:
> >
> > > Both clusters are alive, but the terms active/passive means who=E2=80=
=99s
> serving
> > > the data.
> > >
> > > Your =E2=80=98master=E2=80=99 is the HBase cluster which is r/w and s=
erving data.
> > >
> > > Your =E2=80=98slave=E2=80=99 is the cluster that is passive or only s=
erving read only
> > data.
> > >
> > > To your point that active/passive may be incorrect because you can re=
ad
> > > from the passive, too.
> > >
> > > Peer to Peer may be incorrect in that while both are peers, you=E2=80=
=99re
> > > actively writing to one, while the other gets a copy of the data and =
is
> > > passive.
> > > Understanding that in context a HBase cluster can be active for one
> data
> > > set and passive for another.
> > >
> > > Active/Active would be that I could write to either and there would b=
e
> > > some form of eventual consistency.
> > >
> > > On Nov 28, 2014, at 1:15 AM, Misty Stanley-Jones <
> > > mstanleyjones@cloudera.com <javascript:;>> wrote:
> > >
> > > > I don't think active/passive is what we mean here, since both
> clusters
> > > are
> > > > fully "active" from the perspective of clients, right? The slave
> > cluster
> > > is
> > > > not actually read-only, is it?
> > > >
> > > > On Thu, Nov 27, 2014 at 10:50 PM, Michael Segel <
> > > michael_segel@hotmail.com <javascript:;>>
> > > > wrote:
> > > >
> > > >> master - master?
> > > >>
> > > >> Do you mean active - active ?
> > > >>
> > > >> replace master and slave with active and passive.
> > > >>
> > > >>
> > > >> On Nov 25, 2014, at 3:26 AM, Misty Stanley-Jones <
> > > >> mstanleyjones@cloudera.com <javascript:;>> wrote:
> > > >>
> > > >>> Hi all,
> > > >>>
> > > >>> I think "master-master" is a term that should be re-thought. It i=
s
> > 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 changi=
ng
> > our
> > > >>> terminology?
> > > >>>
> > > >>> Thanks,
> > > >>> Misty
> > > >>
> > > >>
> > >
> > >
> >
>

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