Message-ID: <4E7A0F3E.4050204@timbira.com>
Date: Wed, 21 Sep 2011 13:22:22 -0300
From: Euler Taveira de Oliveira <euler@timbira.com>
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To: pgsql-hackers@postgresql.org
CC: linas.virbalas@continuent.com
Subject: Re: Hot Backup with rsync fails at pg_clog if under load
References: <CA9FD2FE.1D8D2%linas.virbalas@continuent.com>
In-Reply-To: <CA9FD2FE.1D8D2%linas.virbalas@continuent.com>
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On 21-09-2011 11:44, Linas Virbalas wrote:

[This question doesn't belong to -hackers. Please post it in -general or -admin]

> Procedure:
>
> 1. Start load generator on the master (WAL archiving enabled).
> 2. Prepare a Streaming Replication standby (accepting WAL files too):
> 2.1. pg_switch_xlog() on the master;
You don't need this.

> 2.2. pg_start_backup(Obackup_under_loadą) on the master (this will take a
> while as master is loaded up);
No. if you use pg_start_backup('foo', true) it will be fast. Check the manual.

> 2.3. rsync data/global/pg_control to the standby;
Why are you doing this? If ...

> 2.4. rsync all other data/ (without pg_xlog) to the standby;
you will copy it again or no? Don't understand your point.

> 2.5. pg_stop_backup() on the master;
> 2.6. Wait to receive all WAL files, generated during the backup, on the
> standby;
> 2.6. Start the standby PG instance.
>
> The last step will, usually, fail with a similar error:
>
The problem could be that the minimum recovery point (step 2.3) is different 
from the end of rsync if you are under load.


-- 
    Euler Taveira de Oliveira - Timbira       http://www.timbira.com.br/
    PostgreSQL: Consultoria, Desenvolvimento, Suporte 24x7 e Treinamento