From owner-freebsd-performance@FreeBSD.ORG Mon Aug 25 21:20:47 2003 Return-Path: Delivered-To: freebsd-performance@freebsd.org Received: from mx1.FreeBSD.org (mx1.freebsd.org [216.136.204.125]) by hub.freebsd.org (Postfix) with ESMTP id BFDF916A4BF for ; Mon, 25 Aug 2003 21:20:47 -0700 (PDT) Received: from perrin.nxad.com (internal.ext.nxad.com [69.1.70.251]) by mx1.FreeBSD.org (Postfix) with ESMTP id 3FCE143FE5 for ; Mon, 25 Aug 2003 21:20:47 -0700 (PDT) (envelope-from sean@nxad.com) Received: by perrin.nxad.com (Postfix, from userid 1001) id 4C26120F01; Mon, 25 Aug 2003 21:20:46 -0700 (PDT) Date: Mon, 25 Aug 2003 21:20:46 -0700 From: Sean Chittenden To: Rod Taylor Message-ID: <20030826042046.GC1514@perrin.nxad.com> References: <200308250929.32143.paul@pathiakis.com> <20030826030527.GB1514@perrin.nxad.com> <1061869321.3193.9.camel@jester> Mime-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="XsQoSWH+UP9D9v3l" Content-Disposition: inline In-Reply-To: <1061869321.3193.9.camel@jester> X-PGP-Key: finger seanc@FreeBSD.org X-PGP-Fingerprint: 3849 3760 1AFE 7B17 11A0 83A6 DD99 E31F BC84 B341 X-Web-Homepage: http://sean.chittenden.org/ User-Agent: Mutt/1.5.4i cc: freebsd-performance@freebsd.org cc: Paul Pathiakis Subject: Re: Tuning Postgresql on FreeBSD 5.1 X-BeenThere: freebsd-performance@freebsd.org X-Mailman-Version: 2.1.1 Precedence: list List-Id: Performance/tuning List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Tue, 26 Aug 2003 04:20:47 -0000 --XsQoSWH+UP9D9v3l Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable > > while still maintaining reasonable file system performance (ext2 is > > faster than ext3 by a wide margin, but ext2 is _not_ a reliable FS). >=20 > > > #fsync =3D true > >=20 > > Change this to false. >=20 > This is a funny thing to suggest after the filesystem comment. :) Did you enjoy that? :) I should clarify that piece of "advice" though. If you're _sure_ power isn't going to fail (using a UPS) and make regular backups (standard operating procedure), then fsync =3D false can be a good thing in terms of performance (roughly speaking, it doubles performance of any write/update operation). A disk failure is a disk failure and there is no substitute for RAID. Leaving stability in the OS and PostgreSQL... this is a FreeBSD mailing list, stability goes without saying. :) That said though, if you're unable to stomach the possibility of possibly loosing data when one of the above fails, keep fsync =3D true. If, however, you have mitigated the risks to levels that your business/operation is comfortable with (your data center is on generators, your DB systems have UPSs, are using RAID, and make frequent backups), then I would set fsync =3D false for most noncritical apps (non-financial, non-medical). -sc --=20 Sean Chittenden --XsQoSWH+UP9D9v3l Content-Type: application/pgp-signature Content-Disposition: inline -----BEGIN PGP SIGNATURE----- Comment: Sean Chittenden iD8DBQE/SuAe3ZnjH7yEs0ERAmUiAKChZA4sZaHOUi5ia0TDywtMri2FtACfXU8W l4+GrFca0eDgWvWsWSlCAHk= =3jT7 -----END PGP SIGNATURE----- --XsQoSWH+UP9D9v3l--