[pgpool-general: 6470] Re: trusted_servers

[Alexander Dorogensky]

Thanks for a very detailed explanation!

How long can it take pgpool to detect that the trusted server (one) is not
responsive?

We're using pgpool 3.6.9 and we have 2 node (primary/standby postgres
cluster with streaming replication) configuration and each node has pgpool.

We had to set trusted_servers because otherwise pgpool wouldn't detect
network partition events such as when
network interface goes down on one of the nodes. So I believe in this
configuration we wouldn't have been able to use
the pgpool's split-brain syndrome auto detection?

Thank you Muhammad!





On Wed, Mar 20, 2019 at 8:23 AM Muhammad Usama <m.usama at gmail.com> wrote:

> Hi
>
> On Wed, Mar 13, 2019 at 6:28 PM Alexander Dorogensky <
> amazinglifetime at gmail.com> wrote:
>
>> Hi everyone,
>>
>> We generally set this parameter to one host to remedy split brain
>> situations but some customers have unreliable networks and therefore ping
>> to that host would fail and pgpool would shut down.
>>
>> My understanding was that trusted server(s) connection will only be
>> tested after degenerated state was detected (before triggering failover),
>> is it correct?
>>
>> If not.. how do I configure trusted servers in a flaky network?
>>
>
> No thats not correct, If the trusted_server(s) are configured than
> Pgpool-II try to ping the trusted_servers after every life-check interval
> (wd_interval),
>
> Basically the trusted_servers checking was introduced in the pgpool
> watchdog, during the early days of watchdog, and as you mentioned its
> purpose was to
> mitigate the split-brain syndrome, by making sure that the Pgpool-II node
> which gets isolated from the network because of network partitioning or
> some other network issue removes itself from the Pgpool-II cluster.
>
> But since Pgpool-II 3.5 there have been lots of enhancements made to the
> Pgpool-II watchdog specifically in the area of guarding against the
> split-brain and
> other similar scenarios, and the latest versions of Pgpool-II does not
> require trusted_servers configuration to detect and avoid split-brain.
>
> So if you are using the Pgpool-II > V 3.5 and the Pgpool-II cluster is
> configured with odd number of nodes (>=3) than you can safely disable the
> trusted_server
> configuration, and watchdog will take care of split-brain issue itself.
>
> Thanks
> Best Regards
> Muhammad Usama
>
>
>
>> Thanks
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>
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