[pgpool-hackers: 3983] Re: [pgpool-general: 7543] VIP with one node

[Muhammad Usama]

On Sun, Jul 18, 2021 at 11:31 AM Tatsuo Ishii <ishii at sraoss.co.jp> wrote:

> > Hi Ishii_San
> >
> > Your understanding is correct for the proposal. Basically IMHO whatever
> we
> > do for trying to remedy that original issue there will always be a chance
> > of split-brain.
>
> Right.
>
> > The reason I am proposing this solution is that with this proposed design
> > the behaviour
> > would be configurable. For example if user set
> wd_lost_node_to_remove_timeout
> > = 0
> > then this will disable the lost node removal function and eventually the
> > watchdog would
> > behave as it does currently.
> > And normally I expect this wd_lost_node_to_remove_timeout value to be set
> > in the
> > range of 5 to 10 mins. Because blackout for more than 5 to 10 mins would
> > mean
> > there is some serious problem in the network that a node is unable to
> > community for
> > such a long period of time and we need resume the service even if it
> comes
> > with
> > the risk of a split-brain.
>
> Ok.
>
> > The second part of proposal talks about the nodes that are properly shut
> > down. In that
> > case, the proposal is to stop counting those nodes towards the quorum
> > calculation since
> > we already know that these nodes are not alive anymore.
>
> Is it possible to configure watchdog to enable the lost node removal
> function only when a node is properly shutdown?
>
> Yes if we disable the wd_lost_node_to_remove_timeout (by setting it to 0)
the lost node removal will only happen for properly shutdown nodes.

Best Regards
Muhammad Usama


> > But again it also
> > have associated
> > risks in case the previously shutdown node got started again but unable
> to
> > communicate
> > with existing cluster.
>
> Fair point.
>
> Best regards,
> --
> Tatsuo Ishii
> SRA OSS, Inc. Japan
> English: http://www.sraoss.co.jp/index_en.php
> Japanese:http://www.sraoss.co.jp
>
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