On Tue, May 16, 2006 at 12:09:44PM -0700, Richard Yen wrote:
> Hi all,
> 
> Perhaps this is a very very dumb question, but I was wondering if  
> this would be possible, as it would be a very *clean* way for us to  
> do a switchover.
> 
> I've got a cluster of machines, labeled db1, db2, and db3.  db1 is  
> master, and db2 and db3 are slaves.
> 
> We're having segfault issues with postgres on db1, so we were  
> thinking about swapping the db1 and db3 machines to determine if it's  
> a hardware issue, to maintain reliable service while we figure out  
> what's wrong with the machine (if any), etc.
> 
> I figure if I swap names and IP addresses on db1 and db3, then do  
> some sort of MOVE SET call, I'd only have to manipulate settings on 2  
> machines as opposed to more.
> 
> The reason why I want do do this is because we've got 20+ other  
> machines that perform data manipulation on db1, and it would be quite  
> a messy task to have them all point to db3...might miss a few  
> machines....eek.
> 
> I've tried to do this earlier, but to no avail.  Would anyone out  
> there know how to do this successfully?
> 
> Here's what I tried (on a dev environment, of course):
> Take db1 and db3 down
> Swap names and IP addresses (reboot)
> Change sl_path to have the right conninfo
> Change sl_subscribe to point to the right origin
> Restart slon
> Do a MOVE SET
> 
> Am I missing anything?
> 
> Any help would be greatly appreciated...if this is not possible, I'll  
> just go ahead and change the settings on those 20+ machines

If you do end up changing the settings on all of those machines, I have a
suggestion for you. Set up a name in your dns to point to the origin database
(eg. db_origin.yourdomain) and have the 20+ machines refer to that name. Then
when you hit a situation like this, you move set to the new origin and make
the change in your dns and all of your machines will be going to the right
place.

> 
> Thanks!
> --Richard
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-- 
Tim Goodaire    416-673-4126    tgoodair at ca.afilias.info
Database Administrator, Afilias Canada Corp.
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