Re: Setting up HA postgresql

Maybe Linux-HA which you recommended is the more promising option for open
source tool.
http://www.linux-ha.org/wiki/Main_Page

The Postgres resource agent appears to monitor the instance by executing
'SELECT now();' which is typically the recommended check. Though, I do not
know Linux-HA well enough to know of any limitations or whether it should
be recommend
http://linux-ha.org/doc/man-pages/re-ra-pgsql.html

*Will J. Dunn*
*willjdunn.com <http://willjdunn.com>*

On Tue, Jul 21, 2015 at 5:35 PM, William Dunn <dunnwjr(at)gmail(dot)com> wrote:

> On Tue, Jul 21, 2015 at 5:12 PM, Joshua D. Drake <jd(at)commandprompt(dot)com>
> wrote:
>>
>>
>> "When backend node status changes by failover etc., watchdog notifies the
>> information to other pgpool-IIs and synchronizes them. When online recovery
>> occurs, watchdog restricts client connections to other pgpool-IIs for
>> avoiding inconsistency between backends."
>
>
> You're taking that out of context, though. That is coming from the doc
> http://www.pgpool.net/docs/latest/pgpool-en.html#watchdog, which is
> describing how Watchdog coordinates fault of *pgpool-II* backend
> processes and coordinates the pgpool-II instances with each other. It is
> for maintaining availability of pgpool-II and monitoring for failure of
> pgpool-II backends, not Postgres/postmaster.
>
> *Will J. Dunn*
> *willjdunn.com <http://willjdunn.com>*
>
> On Tue, Jul 21, 2015 at 5:12 PM, Joshua D. Drake <jd(at)commandprompt(dot)com>
> wrote:
>
>>
>> On 07/21/2015 01:37 PM, William Dunn wrote:
>>
>>> But it appears that the fail condition for "watchdog" is the failure of
>>> a pgpool-II instance. In the configuration described in the wiki you
>>> would put a pgpool-II instance on each Postgres node, and if one of the
>>> pgpool-II instances fails it executes a script (which can create the
>>> trigger file to promote the standby to master). However, if the fail
>>> condition for watchdog is a failure of the pgpool-II instance what
>>> happens if the DBMS has availability issues but the pgpool-II process on
>>> that server is ok? The fail condition would never be triggered, right?
>>>
>>
>> What I am going off of is:
>>
>> "When backend node status changes by failover etc., watchdog notifies the
>> information to other pgpool-IIs and synchronizes them. When online recovery
>> occurs, watchdog restricts client connections to other pgpool-IIs for
>> avoiding inconsistency between backends."
>>
>> A backend node status would change if say the master went down, at that
>> point pgpool can be instructed either automatically or manually to failover
>> (depending on configuration) and allow the slave to failover.
>>
>> Sincerely,
>>
>>
>> JD
>>
>> --
>> Command Prompt, Inc. - http://www.commandprompt.com/ 503-667-4564
>> PostgreSQL Centered full stack support, consulting and development.
>> Announcing "I'm offended" is basically telling the world you can't
>> control your own emotions, so everyone else should do it for you.
>>
>
>