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Subject: Re: Multi node topology
From: Adam Kocoloski <kocolosk@apache.org>
In-Reply-To: <2C7BACD2-5BCA-4D49-8355-1032E73937FB@lidalia.org.uk>
Date: Fri, 19 Aug 2011 14:29:23 -0400
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To: user@couchdb.apache.org

Hi Robert, no, I wouldn't say that.  The projects Paul mentioned can =
simplify some of the setup of a multi-master deployment even if you =
don't take advantage of the sharding, but they're by no means required =
for it.

To answer your questions, push and pull replications are approximately =
equal in their efficiency these days.  The approach you outlined should =
be fine for a cluster of 4 nodes.  Cheers,

Adam

On Aug 19, 2011, at 2:21 PM, Robert Elliot wrote:

> Thanks; we're aware of both solutions, but as we do not currently need =
to partition/shard we are interested in exploring what CouchDB could do =
by itself, since it supports bi-directional replication.
>=20
> Is the answer "the CouchDB developers recommend not running CouchDB in =
a multi-master replicated topology"?
>=20
> On 19 Aug 2011, at 18:26, Paul Davis wrote:
>=20
>> Robert,
>>=20
>> There are two projects for running CouchDB in a cluster:
>> CouchDB-Lounge and BigCouch. CouchDB-Lounge is a combination of an
>> nginx module and Python proxy that handles managing multiple backend
>> CouchDB nodes. BigCouch is a pure Erlang implementation that works
>> more like Dynamo.
>>=20
>> [1] http://tilgovi.github.com/couchdb-lounge/
>> [2] http://github.com/cloudant/bigcouch
>>=20
>> On Fri, Aug 19, 2011 at 8:32 AM, Robert Elliot <rob@lidalia.org.uk> =
wrote:
>>> Hi,
>>>=20
>>> We are considering setting up a cluster with more than two nodes. =
There is a lot of documentation regarding two nodes but we couldn't find =
an exact answer for let's say a cluster of 4 nodes.
>>>=20
>>> Would you recommend a multi-master setup where all nodes receive =
writes?  This would be simpler to setup and administer, and would also =
be the most fault tolerant (any combination of nodes can be shutdown so =
long as one is still active).
>>>=20
>>> If so, should we use only push replication?  Or only pull =
replication?  Or a combination of both?
>>>=20
>>> Assuming we are using pull replication within 4 nodes: A, B, C and =
D. Should we set up A to pull changes from B, C and D, B to pull changes =
from A, C and D, C to pull changes from A, B and D and D to pull changes =
from A, B and C? Is this the recommended approach?
>>>=20
>>> Thanks for any guidance,
>>>=20
>>> Rob
>>>=20
>=20