Re: Setting up HA postgresql - Mailing list pgsql-general

From Joshua D. Drake
Subject Re: Setting up HA postgresql
Date
Msg-id 55AEB5C4.6050504@commandprompt.com
Whole thread Raw
In response to Re: Setting up HA postgresql  (William Dunn <dunnwjr@gmail.com>)
Responses Re: Setting up HA postgresql  (William Dunn <dunnwjr@gmail.com>)
List pgsql-general
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

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