[pgpool-general: 5383] Re: [pgpool] Streaming Replication - Identify Slave Node Status

Anushka Weerakkodyge anushkaw at ceylonit.com
Thu Mar 23 02:12:12 JST 2017


Thank you for these tips. pgpool failover seems consistent now.


Thanks,
Anushka

On Wed, Mar 22, 2017 at 6:59 PM, Lazaro Garcia <lazaro3487 at gmail.com> wrote:

> Pgpool triggers failover on this situations:
>
>
>
> With health_check functionality. Between intervals it checks the status of
> backends nodes and makes a failover if a node is detected as down.
>
>
>
> fail_over_on_backend_error: If this command is set to on,  Initiates
> failover when reading/writing to the backend communication socket fails. If
> set to off, pgpool will report an error and disconnect the session.
>
>
>
> Check these configurations.
>
>
>
> And start pgpool with –D option for descarting pgpool_status file.
>
>
>
> Regards.
>
>
>
> *De:* Anushka Weerakkodyge [mailto:anushkaw at ceylonit.com]
> *Enviado el:* miércoles, 22 de marzo de 2017 04:37 a. m.
> *Para:* Lazaro Garcia
> *CC:* pgpool-general at pgpool.net
> *Asunto:* Re: [pgpool-general: 5370] [pgpool] Streaming Replication -
> Identify Slave Node Status
>
>
>
> Hi Lazaro,
>
>
>
> I tried failover command in pgpool and was able to stop the replication
> and make the master server a read only node when the standby is down. But I
> noticed that this procedure does not work always. Sometimes pgpool does not
> trigger failover mechanism when the standby node is down and log keeps
> showing *failed to make persistent db connection *message. Is there
> something I'm missing here ?
>
>
>
> In the config file I turned on master_slave mode and load_balance mode.
>
>
>
>
>
>
>
>
>
>
> Thanks,
>
> Anushka
>
>
>
> On Fri, Mar 17, 2017 at 5:10 AM, Anushka Weerakkodyge <
> anushkaw at ceylonit.com> wrote:
>
> Thank you! I will try this method definitely. By the way, what I really
> need is to fail the transaction when slave is down. Using this method I can
> identify the status of the slave node, then will try to make the master
> node read only until the slave comes online.
>
>
>
>
> Thanks,
>
> Anushka
>
>
>
> On Thu, Mar 16, 2017 at 6:36 PM, Lazaro Garcia <lazaro3487 at gmail.com>
> wrote:
>
> When slave goes down, pgpool detects that and triggers a failover, then
> the master remains active and the slave are marked as down state. On the
> failover_command of pgpool, you could execute a command that drop the slave
> from the master synchronous_standby_names and reload the configuration on
> the master. By this way new transactions can be executed on the master
> without checking the state of the slave because synchronous replication has
> been disabled.
>
>
>
> If you recover the slave you can attach this server to master again an
> activate the synchronous replication.
>
>
>
> Regards.
>
>
>
>
>
> *De:* pgpool-general-bounces at pgpool.net [mailto:pgpool-general-
> bounces at pgpool.net] *En nombre de *Anushka Weerakkodyge
> *Enviado el:* miércoles, 15 de marzo de 2017 05:37 p. m.
> *Para:* pgpool-general at pgpool.net
> *Asunto:* [pgpool-general: 5370] [pgpool] Streaming Replication -
> Identify Slave Node Status
>
>
>
> Hi all,
>
>
>
> I have a synchronous streaming replication environment which is
> implemented using inbuilt replication mechanism in postgresql. There is a
> requirement that I need to fail the data modification transactions on
> master node if the slave node is down. (ie: transactions should commit when
> only both servers are up and running)
>
>
>
> Please let me know whether there is a way to identify slave node status
> and fail the transaction using pgpool ?
>
>
>
> Thanks,
>
> Anushka
>
>
>
>
>
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