> 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?
No. The condition (PostgreSQL failure) will be detected by one of
pgpool-II (not watchdog process) and the pgpool-II will disconnect the
failed PostgreSQL, then execute failover script (if defined) which
will usually promote standby PostgreSQL (if failed PostgreSQL was
primary) or just ignore the broken PostgreSQL if it was standby.
Best regards,
--
Tatsuo Ishii
SRA OSS, Inc. Japan
English: http://www.sraoss.co.jp/index_en.php
Japanese:http://www.sraoss.co.jp
> *Will J. Dunn*
> *willjdunn.com <http://willjdunn.com>*
>
> On Tue, Jul 21, 2015 at 4:27 PM, Joshua D. Drake <jd@commandprompt.com>
> wrote:
>
>>
>> On 07/21/2015 01:21 PM, William Dunn wrote:
>>
>>> That's pretty cool! But the intended use of watchdog is so you can have
>>> multiple pgpool-II instances and failover among them
>>> (http://www.pgpool.net/docs/latest/pgpool-en.html#watchdog) rather than
>>> failure of Postgres. In the configuration described in that wiki what
>>> happens when the DBMS goes down but pgpool-II is fine? The watchdog
>>> appears to be monitoring the pgpool-II process, not the
>>> postgres/postmaster process.
>>>
>>
>> From what I see, it has the ability to execute a command/script based on a
>> failed condition which could include but not be limited to a command to
>> fail over a standby.
>>
>>
>> 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.
>>
