Actually, in my case Slony does work well in LAN but does not work at
all over WAN.  As I understand it, at least one of the slon processes
(perhaps both) need to communicate with both the master and the slave
DB.  If the slon process runs in the same location as the master, then
it needs to communicate with the slave over WAN.  If it runs in the same
location as the slave then it needs to communicate with the master over
WAN.  One way or another you'll have a slon process talking across the
WAN to some DB.  And in our case that simply didn't work.  There was
enough flakiness in the network between the slon process and the DB that
replication never got going.

As I understand it, if you have a WAN scenario, you need to use slony
*logshipping* (not to be confused with "standard" slony replication).
I've successfully set up slony logshipping across the WAN, but it's a
bit of a pain to set up.

--S


-----Original Message-----
From: slony1-general-bounces at lists.slony.info
[mailto:slony1-general-bounces at lists.slony.info] On Behalf Of Mark
Steben
Sent: Thursday, August 21, 2008 1:53 PM
To: 'Bill Moran'; 'Vivek Khera'
Cc: slony1-general at lists.slony.info
Subject: RE: [Slony1-general] Slony over a WAN?

Thank you Bill and Vivek for your prompt responses.

Mark
 
 

-----Original Message-----
From: Bill Moran [mailto:wmoran at collaborativefusion.com] 
Sent: Thursday, August 21, 2008 4:44 PM
To: Mark Steben
Cc: slony1-general at lists.slony.info
Subject: Re: [Slony1-general] Slony over a WAN?

In response to "Mark Steben" <msteben at autorevenue.com>:

> 
> Looking for advice on how to proceed.  We are running Postgres 8.2.5
in
Lee,
> Massachusetts.  We will be installing same in Norfolk Virginia in the
not
> too distant future.  Our need is to replicate roughly 60 - 70 percent
> Of our 80 GB database in Lee over a WAN to Norfolk for reporting
purposes.
> In reading 'Slony-1 Best Practices' on the Website I came across the
> following statement:
>      
>   slon processes should run in the same "network context" as the node
that
> each is responsible for managing so that the connection to that node
is a
> "local" one. 
>      Do not run such links across a WAN.
> 
> Does this still hold true?  If not I would like to hear experiences of
> anyone engaging in a 'Slony-1 long distance relationship'
> Any other alternatives to consider?  I do run Slony-1.2.14 in
development
> with everything encompassed in Lee.  However 
> we will be opening another office 35 miles west in West Springfield
that I
> will be operating out of.  I plan on employing Slony-1
> To provide replication between these 2 'not so long distance'
locations.
> 
> Any comments welcome.  Thanks

I suspect that you're misinterpreting that statement to mean that Slony
doesn't work over a WAN.  It works very well over a WAN in my
experience.

That statement is saying that the individual slon daemons should run
on the same machine or a machine very close to the machine that they
are connecting to as their primary system.  I.e. if you're running a
slon daemon in Mass, it should not have in it's slon.conf a connection
string to the server in Virginia.  There should be one slon running
in Mass that connects to the Mass DB, and a second one running in
Norfolk that connects to the Norfolk DB.

-- 
Bill Moran
Collaborative Fusion Inc.
http://people.collaborativefusion.com/~wmoran/

wmoran at collaborativefusion.com
Phone: 412-422-3463x4023

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