Re: 8.3 synchronous_commit

From: Florian Weimer <fweimer(at)bfk(dot)de>
To: "Guillaume Smet" <guillaume(dot)smet(at)gmail(dot)com>
Cc: "Hannes Dorbath" <light(at)theendofthetunnel(dot)de>, pgsql-performance(at)postgresql(dot)org
Subject: Re: 8.3 synchronous_commit
Date: 2008-01-22 08:56:51
Message-ID: 821w8ame5o.fsf@mid.bfk.de
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* Guillaume Smet:

> On Jan 22, 2008 9:32 AM, Florian Weimer <fweimer(at)bfk(dot)de> wrote:
>> > Maybe it's just my test box.. single SATA-II drive, XFS on top of LVM.
>>
>> Ours was ext3, no LVM or RAID.
>
> Also with SATA?

Yes, desktop-class SATA.

> If your SATA disk is lying about effectively SYNCing the data, I'm
> not that surprised you don't see any improvement.

It still should be faster since the commit doesn't even have to leave
the kernel write cache. For us, this is the common case because most
non-desktop systems have battery-backed write cache anyway.

> Being slower is a bit surprising though.

Exactly.

--
Florian Weimer <fweimer(at)bfk(dot)de>
BFK edv-consulting GmbH http://www.bfk.de/
Kriegsstraße 100 tel: +49-721-96201-1
D-76133 Karlsruhe fax: +49-721-96201-99

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