Re: Streaming Replication Without Downtime

On Tue, Feb 21, 2017 at 6:53 AM, Gabriel Ortiz Lour <ortiz(dot)admin(at)gmail(dot)com>
wrote:

> Hi!
>
> Thanks for pointing out pg_basebackup
>
> The issue I'm facing now is about missing WAL files.
>
> What i'm doing:
> # su postgres -c 'pg_basebackup -D /var/lib/postgresql/9.1/main/ -x -h
> master -U sa_rep' ; service postgresql start
>
> The idea is to call "postgresql start" as soon as pg_basebackup ends.
> But I'm getting the following error:
>
> FATAL: could not receive data from WAL stream: FATAL: requested WAL
> segment XXXXXXX has already been removed
>
> Shoud I just increase 'wal_keep_segments' ?
>

Yes, that is the way to go. But, you need to know what number you need to
increase the wal_keep_segments to ?
Which purely depends on the number of WALs being generated. Which version
of PostgreSQL are you using by the way ?

> If I do so, do I need do restart the master or just a reload will do it?
>

No need to restart, "reload" will do.

Venkata B N
Database consultant

> ---------- Forwarded message ----------
> From: Achilleas Mantzios <achill(at)matrix(dot)gatewaynet(dot)com>
> Date: 2017-02-17 11:20 GMT-02:00
> Subject: Re: [GENERAL] Streaming Replication Without Downtime
> To: pgsql-general(at)postgresql(dot)org
>
>
> Gabriel you are thinking this in the correct way, but its really :
>
> pg_basebackup -D <your data dir> --write-recovery-conf --progress
> --xlog-method=stream -h <your primary db server>
> then you just edit recovery.conf (if needed), tweak postgersql.conf (if
> needed) and start the standby .
>
> On 17/02/2017 15:09, Gunnar "Nick" Bluth wrote:
>
> (sorry for the toppost, mobile device)
> What you're looking for is pg_basebackup with - - xlog=stream, I guess.
>
> Regards,
>
> Nick
>
>
> Am 17. Februar 2017 14:06:36 MEZ schrieb Gabriel Ortiz Lour
> <ortiz(dot)admin(at)gmail(dot)com> <ortiz(dot)admin(at)gmail(dot)com>:
>>
>> Hi all,
>> I've been searching for a way to initialize a new Hot Standby node with
>> Streaming Replication withou the need for stop or even restarting the
>> master.
>> Of course the master is already with the needed SR configs.
>>
>> I know I have to use pg_start_backup/pg_stop_backup, but i'd like some
>> tips, or a link to some tutorial, with the order of the steps.
>>
>> I assume will be something like:
>>
>> - configure Slave for SR
>> - pg_start_backup()
>> - rsync PGDATA to slave
>> - start PG on the slave
>> - pg_stop_backup()
>>
>> Anything i'm thinking wrong?
>>
>> Thanks in advance,
>> Gabriel
>>
>
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> Achilleas Mantzios
> IT DEV Lead
> IT DEPT
> Dynacom Tankers Mgmt
>
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