[Bucardo-general] Syncs are aborted if one of the involved DBs is offline

José Montero jose.montero at brain-tec.ch
Mon Apr 8 07:00:30 UTC 2013

Just a clarification. When I say "Statistically, it is almost 
impossible that the 20 nodes will be online simultaneously", I am 
making a statement about my specific scenario, not about Internet 
connection in a general node. Some nodes of my client are located in 
ships, and these ships may be sailing all around the world. Obviously, 
the Internet connection that a ship can have in the middle of the 
Pacific ocean is null. That's why I say that the 20 nodes will "never" 
be online simultaneously: statistically one of the ships will be 
sailing somewhere with a poor or inexisting Internet connection.

Best regards,

José Montero
Bsc in Computer Engineering
Bsc Master in Computer Science

brain-tec AG
Überlandstrasse 10
CH-3900 Brig

www.brain-tec.ch <http://www.brain-tec.ch>

Am Sun 07 Apr 2013 01:10:41 PM CEST schrieb Michelle Sullivan:
> José Montero wrote:
>> Hello everyone,
>> A client of my company needs a multi-master replication mechanism for
>> PostgreSQL and I have been suggested to use Bucardo. I know the stable
>> version of Bucardo doesn't allow multi-master replication, but the
>> beta version 5 does.
>> I have tested the way Bucardo 5 performs syncs and it looks nice.
>> However, I've encountered a major problem that, according to what I've
>> read in forums, may be an implementation decision:
>>      *A sync is aborted if one of the involved DBs is offline. *
>> My client needs to replicate data among more than 20 nodes.
>> Statistically, it is almost impossible that the 20 nodes will be
>> online simultaneously. Therefore, I really need a sync to synchronize
>> "now" as many databases as possible and later, when the offline
>> databases come online, to synchronize them. Is there a way to achieve
>> what I need using the current version of Bucardo (4.99.7)?
> Whilst I agree with your issue regarding a 'catch up' mode I do disagree
> with your statement 'Statistically, it is almost impossible that the 20
> nodes will be online simultaneously.' ... My nodes are online 99% of the
> time, and whilst I don't have 20 I have 7 all around the world connected
> via the Internet...
> That said, I do support some sort of 'catch up mode'  as a concept.   I
> do have issues with some of the remote nodes going offline from time to
> time, and when they do (particularly due to routing issue of the
> Internet) having replication stop is a major pain the rectum...
> particularly if its due to a hardware failure that takes 24 hours to get
> resolved.  Replication should continue and the host when it comes up
> should be placed into a 'read-only, catch up' mode whilst the catchup
> sync is performed.  All my remote nodes are slave only so it's not too
> much of an issue that way for me, however I do have a cluster of 4
> masters (2 east coast, 2 west cost) that should a master fail it should
> be placed in read-only on startup whilst the DB is synced with
> outstanding changes.  Greg, would this be possible to look at?
> Regards,

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