Re: PostgreSQL replication failover

Hi

You can use repmgr, which is free, or EFM which requires a subscription.

John

> On Jan 14, 2021, at 2:16 AM, Jan Peters <haseningo(at)gmx(dot)de> wrote:
>
> Hello,
>
> thank you very much for the answers.
> Can you tell me some tools, but they must be available for s390 ZLinux.
> For our purposes in redhat linux
>
>
> Gesendet: Mittwoch, 13. Januar 2021 um 19:46 Uhr
> Von: "Ganesh Korde" <ganeshakorde(at)gmail(dot)com>
> An: "Pepe TD Vo" <pepevo(at)yahoo(dot)com>
> Cc: "Jan Peters" <haseningo(at)gmx(dot)de>, pgsql-admin(at)lists(dot)postgresql(dot)org, "Laurenz Albe" <laurenz(dot)albe(at)cybertec(dot)at>
> Betreff: Re: PostgreSQL replication failover
>
> You can use different tools which detects if primary fails and automatically promotes standby.
>
> To assure all data on standby you should use synchronous replication.
>
> On Wed, 13 Jan 2021, 6:54 pm Pepe TD Vo, <pepevo(at)yahoo(dot)com[mailto:pepevo(at)yahoo(dot)com]> wrote:
>
>>> If you shut down the primary server cleanly, all changes will be replicated,so you should be good.
>
>>> During a failover, that is, if the primary suddenly fails, there is always
> the possibility that you lose some transactions, unless you use synchronous
> you said above which I don't need to run promote to make it failover as long as I set synchronous on? The last couple of weeks I have a failure on the primary server and can't run on a slave. It picks up as reading mode only.
>
>
> Bach-Nga
>
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> On Wednesday, January 13, 2021, 06:25:53 AM EST, Laurenz Albe <laurenz(dot)albe(at)cybertec(dot)at[mailto:laurenz(dot)albe(at)cybertec(dot)at]> wrote:
>
>
>
> On Wed, 2021-01-13 at 09:27 +0100, Jan Peters wrote:
>> we are running postgresqlserver on s390 zLinux machines. The distribution
>> is RedHat 7 and RedHat 8, so we do not have the many x86 tools available.
>>
>> We always run 2 instances with a replication (streaming) async mode, the replica
>> is in hot_standby and we use it for read-only accesses. About the setup we have the following question:
>>
>> How is an orderly failover accomplished? Our current procedure is.
>>
>> 1. primary stop
>> 2. promote replica to primary
>> 3. create standby.signal on old primary
>> 4. change primary_conninfo on old primary
>> 5. start old primary as new replica
>>
>> Is this processing correct? Are there any other steps that simplify a failover?
>> How can we be sure that all changes have been transferred from the old master to the replica?
>
> What you describe is not a failover, but a switchover.
>
> If you shut down the primary server cleanly, all changes will be replicated,
> so you should be good.
>
> During a failover, that is, if the primary suddenly fails, there is always
> the possibility that you lose some transactions, unless you use synchronous
> replication.
>
> Yours,
> Laurenz Albe
> --
> Cybertec | https://www.cybertec-postgresql.com[https://www.cybertec-postgresql.com]
>
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