RE: Help needed for replication issue

Classification: External

Hi Prince,
I dropped standby pg_data directory and took backup from primary and transferred into standby but after creating slot “abyproreplica” and created new db test10 with tables but still I can see this slot is in deactive ?

Could you please suggest further?

max_replication_slots
-----------------------
3
(1 row)

postgres=# select * from pg_replication_slots;
slot_name | plugin | slot_type | datoid | database | temporary | active | active_pid | xmin | catalog_xmin | restart_lsn | confirmed_flush_lsn

--------------------+--------+-----------+--------+----------+-----------+--------+------------+------+--------------+-------------+--------------------
-
amos_prod_replica1 | | physical | | | f | f | | | | |
abyprodreplica1 | | physical | | | f | f | | | | |
(2 rows)

postgres=#
From primary:-
postgres=# show max_replication_slots ;
max_replication_slots
-----------------------
3
(1 row)

postgres=# select * from pg_replication_slots;
slot_name | plugin | slot_type | datoid | database | temporary | active | active_pid | xmin | catalog_xmin | restart_lsn | confirmed_flush_lsn

--------------------+--------+-----------+--------+----------+-----------+--------+------------+------+--------------+-------------+--------------------
-
amos_prod_replica1 | | physical | | | f | f | | | | |
abyprodreplica1 | | physical | | | f | f | | | | |
(2 rows)

postgres=#

From: Prince Pathria <prince(dot)pathria(at)goevive(dot)com>
Sent: Friday, April 24, 2020 9:44 PM
To: soumitra bhandary <soumitra(dot)bhandary(at)hotmail(dot)com>
Cc: Ashok kumar Mani <amani(at)accelaero(dot)com>; pgsql-admin(at)postgresql(dot)org; pgsql-admin(at)lists(dot)postgresql(dot)org
Subject: Re: Help needed for replication issue

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Go for pg_basebackup instead of rsync and you'll be happy with the results.
Happy to help :)
Prince Pathria Systems Engineer | Certified Kubernetes Administrator | AWS Solutions Architect Evive +91 9478670472 goevive.com<https://eur03.safelinks.protection.outlook.com/?url=http%3A%2F%2Fgoevive.com%2F&data=02%7C01%7Camani%40accelaero.com%7Ce0be194a26e54436059b08d7e87731cc%7C7bbb8a4d7f1b4a589b3ac250fb8023e3%7C0%7C0%7C637233470962229004&sdata=dCh8ZY8k2XWrQvsJs460nE4sKkCNYytEebiU86GhjOI%3D&reserved=0>

On Fri, Apr 24, 2020 at 7:12 PM soumitra bhandary <soumitra(dot)bhandary(at)hotmail(dot)com<mailto:soumitra(dot)bhandary(at)hotmail(dot)com>> wrote:
Hi Ashok,

Though it is not very clear to identify the issue exactly in the environment.

Few checks you can do .

1. Instead of rsync you can use pgbasebackup -R that will write the recovery.conf with primary slot name.

2. I hope that listen address is properly set and connection between primary and slave node are ok.

3. Do some transaction and execute below query and observe any changes in GB behind

postgres=# SELECT redo_lsn, slot_name,restart_lsn,
round((redo_lsn-restart_lsn) / 1024 / 1024 / 1024, 2) AS GB_behind
FROM pg_control_checkpoint(), pg_replication_slots;

4. If slave is able to consume then this will start reducing .

If problem still persists then check in log of both and find what it suggests .

Have a great day ..

Sent from my iPhone

On 24-Apr-2020, at 9:30 AM, Ashok kumar Mani <amani(at)accelaero(dot)com<mailto:amani(at)accelaero(dot)com>> wrote:


Classification: External

Hi Pathiria,

Step1:- Enable the below parameters in postgresql.conf file for hotstandby

wal_level=replica [ Default : hot_standby]

wal_log_hints = on

synchronous_commit = on

wal_log_hints = on

archive_mode = on [

archive_timeout = 30

archive_command = 'scp %p 172.30.8.199:/data/ARCHIVELOG/%f'

step 2:- #Replication

max_wal_senders = 10

wal_keep_segments = 3200 # in logfile segments, 16MB each; 0 disables[

hot_standby = on

hot_standby_feedback = on # send info from standby to prevent query conflicts

#Log file configurations

log_filename = 'postgresql-%Y-%m-%d_%H%M%S.log'

log_rotation_age = 0

log_rotation_size = 100MB
log_timezone = 'GMT'

Step3:- backup master database then transfer into replica server by using rsync

[postgres(at)de284194 ~]$ psql -c "SELECT pg_start_backup('label', true)"

pg_start_backup

-----------------

10/DA000028

(1 row)

[postgres(at)de284194 pg_data]$ rsync -cva --inplace --exclude=*pg_xlog* \

> ${PGDATA}/ 172.29.7.194:$PGDATA

sending incremental file list

./

pg_wal/archive_status/0000000100000010000000CC.done

pg_wal/archive_status/0000000100000010000000CD.00000028.backup.done

pg_wal/archive_status/0000000100000010000000CD.done

pg_wal/archive_status/0000000100000010000000D5.done

pg_xact/

pg_xact/0000

sent 1,053,663,924 bytes received 21,480 bytes 15,160,941.06 bytes/sec

total size is 1,053,341,161 speedup is 1.00

[postgres(at)de284194 pg_data]$

Step 4:- Stop the backup

[postgres(at)de284194 pg_data]$ psql -c "select pg_stop_backup(), current_timestamp"

NOTICE: pg_stop_backup complete, all required WAL segments have been archived

Step 5;- Create recovery.conf

postgres=# SELECT pg_create_physical_replication_slot('amos_prod_replica1');

pg_create_physical_replication_slot

-------------------------------------

(amos_prod_replica1,)

(1 row)

Start the db server in replica server:-

Regards,
Ashok

From: Prince Pathria <prince(dot)pathria(at)goevive(dot)com<mailto:prince(dot)pathria(at)goevive(dot)com>>
Sent: Thursday, April 23, 2020 1:00 PM
To: Ashok kumar Mani <amani(at)accelaero(dot)com<mailto:amani(at)accelaero(dot)com>>
Cc: pgsql-admin(at)postgresql(dot)org<mailto:pgsql-admin(at)postgresql(dot)org>; pgsql-admin(at)lists(dot)postgresql(dot)org<mailto:pgsql-admin(at)lists(dot)postgresql(dot)org>
Subject: Re: Help needed for replication issue

Information Security Email Alert: This email is from an EXTERNAL source. Please use caution when clicking on links or opening attachments from an unknown or suspicious sender. To report a suspected phishing email, Send us an Email on Servicedesk(at)accelaero(dot)com<mailto:Servicedesk(at)accelaero(dot)com>

Hey Ashok,

Please share the steps you've followed till now so we help further.

Thanks!
Happy to help :)
Prince Pathria Systems Engineer | Certified Kubernetes Administrator | AWS Solutions Architect Evive +91 9478670472 goevive.com<https://eur03.safelinks.protection.outlook.com/?url=http%3A%2F%2Fgoevive.com%2F&data=02%7C01%7Camani%40accelaero.com%7Ce0be194a26e54436059b08d7e87731cc%7C7bbb8a4d7f1b4a589b3ac250fb8023e3%7C0%7C0%7C637233470962238996&sdata=%2BfNjJlmMCyaZNrMvl7hQNNyXtiEW1iCp5rKHy78sZ1Y%3D&reserved=0>

On Thu, Apr 23, 2020 at 11:44 AM Ashok kumar Mani <amani(at)accelaero(dot)com<mailto:amani(at)accelaero(dot)com>> wrote:

Classification: Internal

Dear All,
I have created Postgresql 10.6 hot standb ,but while creating physical replication slots by default it is in inactive more
I recreated the standby but still I am unable to make slots is in active and also I could not able to see the LSN value on both sites.

Regards,
Ashok