Re: [Slony1-general] Slony and streaming replication combo

[David Fetter]

On Wed, Feb 22, 2017 at 05:30:43PM +, Zarko Aleksic wrote:
> Greetings everyone,
> 
> We've recently started considering Slony for purpose of migrating
> PostgreSQL from old physical server to a new virtualized and
> "updated" platform. So far, all our tests worked quite well.
> However, I'm having trouble finding any documentation to prove or
> disprove that the following scenario is supported and/or will work
> properly (initial testing was positive though).

> "New B" (disaster recovery site)   < Streaming replication   "New A" 
>  "Old B" 
> (DR site)

I can see no reason it wouldn't work.  Slony does things that are
pretty much disjoint from what streaming replication does, so they
won't be able to ste on each others' toes.

> We are using slony1-91-II-2.1.4 and Postgres 9.1 on RHEL 6, later we
> will most likely do the same type of migration from 9.1 to 9.5.

If you're using Slony, you might as well go to 9.6.latest while you're
at it.  You won't save time by replicating yet again to another
virtual server, and the chances that going to 9.6 will break something
are much smaller than the chances that staying on the now-defunct 9.1
will.  There have already been data loss bugs that were fixed since
9.1 went out of support, i.e. 9.1 didn't get those fixes applied.

That setup will work nicely with what I hope will become a routine
operation, namely upgrading major versions. :)

Best,
David.
-- 
David Fetter  http://fetter.org/
Phone: +1 415 235 3778  AIM: dfetter666  Yahoo!: dfetter
Skype: davidfetter  XMPP: david(dot)fetter(at)gmail(dot)com

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Re: [Slony1-general] Slony and streaming replication combo

[Jeff Frost]

I've done this. It works fine.

Make sure you install the slony extensions on Old B and New B in the event you 
need to fail over to one of the B nodes.


> On Feb 22, 2017, at 6:52 PM, Steve Singer  wrote:
> 
> I can't think why it wouldn't work. You should be able to do streaming 
> replication from a slony subscriber.
> 
> I have not tried a similar setup myself
> 
> Zarko Aleksic wrote:
>> Greetings everyone,
>> 
>> We've recently started considering Slony for purpose of migrating PostgreSQL 
>> from old physical server to a new virtualized and "updated" platform. So 
>> far, all our tests worked quite well. However, I'm having trouble finding 
>> any documentation to prove or disprove that the following scenario is 
>> supported and/or will work properly (initial testing was positive though).
>> 
>> We would like to setup streaming replication between future Slony subscriber 
>> and our DR site beforehand, ie. before we introduce Slony. This would save 
>> us time and additional work post migration. 
>> 
>> It would look something like this:
>> "New B" (disaster recovery site)   < Streaming replication   "New A" 
>>  "Old B" 
>> (DR site)
>> Streaming replication between "New A" and "New B" would be setup first
>> Then we would setup Slony replication between "Old A" and "New A"
>> Slony replication Set would be moved from "Old A" to "New A"
>> Slon process would be stopped and Slony Schema would be removed 
>> Has anyone done something similar? Are there potential downsides to this 
>> idea? 
>> 
>> We are using slony1-91-II-2.1.4 and Postgres 9.1 on RHEL 6, later we will 
>> most likely do the same type of migration from 9.1 to 9.5. 
>> 
>> Any response is greatly appreciated.
>> Thanks!
>> Zarko
>> 
> Sent Using Firefox OS
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