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 <dunn...@gmail.com> wrote: > On Tue, Jul 21, 2015 at 5:12 PM, Joshua D. Drake <j...@commandprompt.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 <j...@commandprompt.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. >> > >
