Re: Failover, Wal Logging, and Multiple Spares

Ok, I've asked this a few times, but nobody ever responded. I think I
finally got it though, could somebody confirm my logic? Basically, you
setup a chain of servers, and when fails you replicate to the next link in
the chain, like so:
Master (A) --> Warm Standby (B) --> Warn Standby (C) --> etc.

Master Fails, now becomes:

Old Master (A) xxxxx> New Master (B) --> Warm Standby (C)

And, of course, you might have an additional replication chain from Master
(A) just in case you goof something up in the failover process, but that's
the basic idea.

Thanks,
Bryan

On Sun, Aug 16, 2009 at 9:35 PM, Bryan Murphy <bmurphy1976(at)gmail(dot)com> wrote:

> Assuming we are running a Postgres instance that is shipping log files to 2
> or more warm spares, is there a way I can fail over to one of the spares,
> and have the second spare start receiving updates from the new master
> without missing a beat? I can live with losing the old master, and at least
> at the moment it would be a controlled failover, but I would like to to know
> if it's possible during an uncontrolled failover as well (catastrophic
> hardware failure).
> Right now, we have just that setup, but every time I've failed over to the
> new master, we've had to rebuild our spares from scratch and unfortunately
> this is a multi-hour long process. We can't afford the risk of not having a
> warm spare for that length of time. We're planning to move entirely to a
> slony cluster, but I'd like to fail over to a more powerful machine before
> we begin the slony migration as the current server is already overloaded.
>
> Thanks,
> Bryan
>