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Date: Fri, 7 May 2010 10:00:50 -0400
Message-ID: <AANLkTimHV4IKzzjAZHJ9wwejKCm3t5fbsmIYhk4IOZND@mail.gmail.com>
Subject: Re: no universally correct setting for fsync
From: Robert Haas <robertmhaas@gmail.com>
To: Kevin Grittner <Kevin.Grittner@wicourts.gov>
Cc: pgsql-hackers@postgresql.org
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On Fri, May 7, 2010 at 9:47 AM, Kevin Grittner
<Kevin.Grittner@wicourts.gov> wrote:
> Someone just posted to the -admin list with a database corrupted
> while running with fsync=3Doff. =A0I was all set to refer him to the
> documentation explaining why he should stop doing this, but to my
> surprise the documentation waffles on the issue way past what I
> think is reasonable.
>
> http://www.postgresql.org/docs/8.4/interactive/runtime-config-wal.html#GU=
C-FSYNC
>
> There are dire-sounding statements interspersed with:
>
> | using fsync results in a performance penalty
>
> | Due to the risks involved, there is no universally correct setting
> | for fsync.
>
> | If you trust your operating system, your hardware, and your
> | utility company (or your battery backup), you can consider
> | disabling fsync.
>
> Isn't this a little too rosy a picture to paint?

I agree.  I've always thought this part of the documentation made
setting fsync=3Doff much more reasonable than I feel it to be.

--=20
Robert Haas
EnterpriseDB: http://www.enterprisedb.com
The Enterprise Postgres Company