[pgpool-general: 363] Re: Multiple pgpool servers failover

Matt Wise matt at nextdoor.com
Fri Apr 20 22:10:27 JST 2012

  The problem with that (and that was our original idea) DISALLOW does not function in the way we want. When DISALLOW is set, if any server in your pool of 4 DB servers goes down, access to all of them is hung. Worse yet, if the master changes from say DB1 to DB2 (and you bring DB1 back up as a slave of DB2), the non-controlling PGPool in DISALLOW mode will never notice.


On Apr 19, 2012, at 10:48 PM, Ludwig Adam wrote:

> Dear Lou, why would you use multiple pgpool instances to control failover?
> Perhaps it would be a solution to have one instance of pgpool to set to FAILOVER and the others to DISALLOW...? 
> Ludwig 
> Mobil gesendet.
> -----Original Message----- 
> From: Lou Kamenov [kamenovl at defx.org]
> Received: Freitag, 20 Apr. 2012, 3:54
> To: Matt Wise [matt at nextdoor.com]
> CC: pgpool-general at pgpool.net [pgpool-general at pgpool.net]
> Subject: [pgpool-general: 360] Re: Multiple pgpool servers failover
> On Thu, Apr 19, 2012 at 9:32 PM, Matt Wise <matt at nextdoor.com> wrote:
> [..]
> > If DISALLOW_TO_FAILOVER is set and ..
> >   a) one of the slaves fails: that slave is taken out of rotation until its
> > back up
> >   b) the master fails: all connections hang until the master is back, OR a
> > new master is detected. pgpool goes into a loop looking for new masters.
> I was thinking more about section B, my problem is essentially an
> atomic fail-over,
> where we are ensured that this is triggered only once.
> I will give it a shot and post back my findings.
> If anyone else has any ideas, please send them over ;)
> cheers,
> Lou
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