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Date: Tue, 10 Nov 2009 16:29:32 +0100
Message-ID: <8a1bfe660911100729q42ac732cga9bbadd52e2533dd@mail.gmail.com>
Subject: Re: limiting performance impact of wal archiving.
From: Laurent Laborde <kerdezixe@gmail.com>
To: Ivan Voras <ivoras@freebsd.org>
Cc: pgsql-performance@postgresql.org
Content-Type: text/plain; charset=ISO-8859-1

On Tue, Nov 10, 2009 at 4:11 PM, Ivan Voras <ivoras@freebsd.org> wrote:
> Laurent Laborde wrote:
>
> Ok, this explains it. It also means you are probably not getting much
> runtime performance benefits from the logging and should think about moving
> the logs to different drive(s), among other things because...

It is on a separate array which does everything but tablespace (on a
separate array) and indexspace (another separate array).

>> Of course, when doing sequential read it goes to +250MB/s :)
>
> ... it means you cannot dedicate 0.064 of second from the array to read
> through a single log file without your other transactions suffering.

Well, actually, i also change the configuration to synchronous_commit=off
It probably was *THE* problem with checkpoint and archiving :)

But adding cstream couldn't hurt performance, and i wanted to share
this with the list. :)

BTW, if you have any idea to improve IO performance, i'll happily read it.
We're 100% IO bound.

eg: historically, we use JFS with LVM on linux. from the good old time
when IO wasn't a problem.
i heard that ext3 is not better for postgresql. what else ? xfs ?

*hugs*

-- 
ker2x
Sysadmin & DBA @ http://www.over-blog.com/