Aw: Re: PostgreSQL replication failover

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@gmail.com>
An: "Pepe TD Vo" <pepevo@yahoo.com>
Cc: "Jan Peters" <haseningo@gmx.de>, pgsql-admin@lists.postgresql.org, "Laurenz Albe" <laurenz.albe@cybertec.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@yahoo.com[mailto:pepevo@yahoo.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
ofweeks 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.albe@cybertec.at[mailto:laurenz.albe@cybertec.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
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