[Pacemaker] Postgresql streaming replication failover - RA needed

[Attila Megyeri]

Hi Florian,

-----Original Message-----
From: Florian Haas [mailto:florian at hastexo.com] 
Sent: 2011. november 16. 11:49
To: The Pacemaker cluster resource manager
Subject: Re: [Pacemaker] Postgresql streaming replication failover - RA needed

Hi Attila,

On 2011-11-16 10:27, Attila Megyeri wrote:
> Hi All,
> 
>  
> 
> We have a two-node postgresql 9.1 system configured using streaming 
> replicaiton(active/active with a read-only slave).
> 
> We want to automate the failover process and I couldn't really find a 
> resource agent that could do the job.

That is correct; the pgsql resource agent (unlike its mysql counterpart) does not support streaming replication. We've had a contributor submit a patch at one point, but it was somewhat ill-conceived and thus did not make it into the upstream repo. The relevant thread is here:

http://lists.linux-ha.org/pipermail/linux-ha-dev/2011-February/018195.html

Would you feel comfortable modifying the pgsql resource agent to support replication? If so, we could revisit this issue and potentially add streaming replication support to pgsql.


Well I'm not sure I would be able to do that change. Failover is relatively easy to do but I really have no idea how to do the failback part. I will definitively have to sort this out somehow, I am just unsure whether I will try to use the repmgr mentioned in the video, or pacemaker with some level of customization...

Is the resource agent that you mentioned available somewhere?

Thanks.
Attila