Re: pg_basebackup fails: could not receive data from WAL stream:server closed the connection unexpectedly

Hi,
Thank you very much for the response.

I reckon we can return to more conventional approach of postgres db synchronization:
1) SELECT pg_start_backup('label', true);
2) rsync/cp  $PGDATA directory;
3) SELECT pg_stop_backup();

In my opinion this approach looks better because it does not depend on wal_sender_timeout value.

I have a question. What is your opinion about pg_basebackup utility and its behaviour for this condition?  Is it a bug? Should it be fixed?

Best regards,
Andrei



From:        Shreeyansh Dba <shreeyansh2014@gmail.com>
To:        AYahorau@ibagroup.eu,
Cc:        pgsql-admin <pgsql-admin@postgresql.org>, MikalaiKeida@ibagroup.eu
Date:        03/12/2018 15:15
Subject:        Re: pg_basebackup fails: could not receive data from WAL stream: server closed the connection unexpectedly

---

Hi Andrei Yahorau,

As it is difficult to give an exact recommendation, however, We have enabled and tested your exact error with the same parameters in our testing environment, we received the same error and able to resolve this problem by increasing 'wal_sender_timeout' parameter value.

I think you need to test and verify before implementing it on your server according to your business, configuration requirements.




On Mon, Dec 3, 2018 at 2:17 PM <AYahorau@ibagroup.eu> wrote:
Hello PostgreSQL Community!


Not so long ago I faced the problem of database synchronization using pg_basebackup utility on linux SLES 12 machine using PostgreSQL 10.4:

pg_basebackup -h host01 -U dbuser  -D /var/PostgresDb   -w
LOG:  standby "pg_basebackup" is now a synchronous standby with priority 1
pg_basebackup: could not receive data from WAL stream: server closed the connection unexpectedly
                This probably means the server terminated abnormally
                before or while processing the request.
pg_basebackup: child process exited with error 1
pg_basebackup: removing contents of data directory "/var/RtpPostgresDb"


PostgreSQL log of master server contain the following error entry:
terminating walsender process due to replication timeout

Currently my configuration is the following:
wal_sender_timeout = 1s
wal_receiver_timeout = 1s
wal_receiver_status_interval = 10s

I see that some people faced this situation:
https://www.postgresql.org/message-id/109968546.289.1460409481048.JavaMail.pbrunnen%40Station8.local
The suggestion was increasing wal_sender_timeout  parameter.

On the one hand I understand that  if my database gets bigger it will require bigger value of wal_sender_timeout. On the other hand I use wal_sender_timeout = 1s on purpose in  order to detect if network bad.

Could you please suggest an appropriate configuration, sensible relations between configuration parameters or any other approach of database synchronization which overcomes this issue?

Thank you in advance,
Andrei Yahorau

-- 
Achilleas Mantzios
IT DEV Lead
IT DEPT
Dynacom Tankers Mgmt