[ClusterLabs] Resource Agents: pgsql vs. pgsqlms

[Jehan-Guillaume de Rorthais]

Hello Ede,

On Wed, 10 Jul 2024 19:18:26 +0200
Ede Wolf <listac at nebelschwaden.de> wrote:

> […] 
> we are about to set up a postgresql 15 ha solution and since we already
> have some experience with pacemaker, this seems the obvious route to go
> first.

Indeed!

> What however is somewhat confusing are the available resource agents. 
> By default the pgsql agent is shipped, at least with debian and
> SLES, that however has a copyright notice dating back to 2012.

I don't know for SLES, but PAF is shipped under Debian and RH/Rocky from
official repositories as package "resource-agents-paf".

> Now, when trying to research postgres and pacemaker, most articles do
> talk about PAF, or the pgsqlms resource. 
> 
> I have so far not been able to find the differences between both,

These are big differences between both agents. Just do some lab with both of
them, you'll find the doc, pre-requisits, setup and management are quite
different.

> and in case PAF is, for one reason or the other, the better or more up
> to date solution, why is it not shipped by default? At least not with
> debian or SLES15?

It is shipped, but not in the "resource-agents" package. This might be
because PAF has been created outside of the clusterlabs repositories, but has
then been accepted there after few years, but in its own repository.

> Since postgres ha is rather new to us and me having been lucky not
> having had to deal with perl so far, just reading the agents
> themselves does not really shed that much light on this issue.  
> 
> So in case there is some documentation on comparing these two, or some
> experience, that would be really helpful

You might find this FAQ entry useful:

https://clusterlabs.github.io/PAF/FAQ.html#why-new-ra-for-postgresql

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