Message-ID: <4E7B5B64.3070206@timbira.com>
Date: Thu, 22 Sep 2011 12:59:32 -0300
From: Euler Taveira de Oliveira <euler@timbira.com>
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To: Linas Virbalas <linas.virbalas@continuent.com>
CC: Robert Haas <robertmhaas@gmail.com>, Florian Pflug <fgp@phlo.org>,
	"pgsql-hackers@postgresql.org" <pgsql-hackers@postgresql.org>
Subject: Re: Hot Backup with rsync fails at pg_clog if under load
References: <CAA11FE2.1DDE2%linas.virbalas@continuent.com>
In-Reply-To: <CAA11FE2.1DDE2%linas.virbalas@continuent.com>
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On 22-09-2011 11:24, Linas Virbalas wrote:
> In order to check more cases, I have changed the procedure to force an
> immediate checkpoint, i.e. pg_start_backup('backup_under_load', true). With
> the same load generator running, pg_start_backup returned almost
> instantaneously compared to how long it took previously.
>
> Most importantly, after doing this change, I cannot reproduce the pg_clog
> error message anymore. In other words, with immediate checkpoint hot backup
> succeeds under this load!
>
Interesting. I remembered someone reporting this same problem but it was not 
reproducible by some of us.

> Do you have ideas why does the Hot Backup operation with
> pg_start_backup('backup_under_load', true) succeed while
> pg_start_backup('backup_under_load') fails under the same load?
>
I don't but if you show us the output of the steps above...

> If needed, I could do that, if I had the exact procedure... Currently,
> during the start of the backup I take the following information:
>
Just show us the output of pg_start_backup and part of the standby log with 
the following message 'redo starts at' and the subsequent messages up to the 
failure.


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