From owner-freebsd-database@FreeBSD.ORG Mon Jul 21 12:26:46 2003 Return-Path: Delivered-To: freebsd-database@freebsd.org Received: from mx1.FreeBSD.org (mx1.freebsd.org [216.136.204.125]) by hub.freebsd.org (Postfix) with ESMTP id A7AAD37B401; Mon, 21 Jul 2003 12:26:46 -0700 (PDT) Received: from perrin.int.nxad.com (internal.ext.nxad.com [69.1.70.251]) by mx1.FreeBSD.org (Postfix) with ESMTP id 313F743FAF; Mon, 21 Jul 2003 12:26:46 -0700 (PDT) (envelope-from sean@nxad.com) Received: by perrin.int.nxad.com (Postfix, from userid 1001) id 2B91A210EF; Mon, 21 Jul 2003 12:26:45 -0700 (PDT) Date: Mon, 21 Jul 2003 12:26:45 -0700 From: Sean Chittenden To: Jason Stone Message-ID: <20030721192645.GB61464@perrin.int.nxad.com> References: <20030721043501.F14379-100000@walter> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20030721043501.F14379-100000@walter> 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-database@freebsd.org cc: freebsd-performance@freebsd.org Subject: Re: Tuning for PostGreSQL Database X-BeenThere: freebsd-database@freebsd.org X-Mailman-Version: 2.1.1 Precedence: list List-Id: Database use and development under FreeBSD List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Mon, 21 Jul 2003 19:26:47 -0000 > > Softupdates on, async off. Softupdates is just a better async. > > postgresql fsync's all its files before returning from a commit in > order to ensure durability, right? Does softupdates interfere with > the functioning of sync(2)/fsync(2)? It can, yes, but that's the risk of soft updates. From tuning(7): Softupdates drastically improves meta-data performance, mainly file creation and deletion. We recommend enabling softupdates on most file systems; however, there are two limitations to softupdates that you should be aware of when determining whether to use it on a file system. First, softupdates guarantees file system consistency in the case of a crash but could very easily be several seconds (even a minute!) behind on pending write to the physical disk. If you crash you may lose more work than otherwise. Secondly, softupdates delays the freeing of file system blocks. If you have a file system (such as the root file system) which is close to full, doing a major update of it, e.g. ``make installworld'', can run it out of space and cause the update to fail. For this reason, softupdates will not be enabled on the root file system during a typical install. > > > I would recommend 4.8 over 5.1. Especially if you intend this > > > to be a production server. 5.1 is not ready for public > > > consumption. > > > > Public consumption, yes. Production consumption, no. > > I recently decided to take up the issue of migrating towards 5.1 at > my company. The way I dealt with it was to publish all of my > services to 5.1 boxes and run regression tests. For me, 5.1 > provided adequate performance, and since 5.1 is on the branch where > all new dev work is going on and 4.x is going to be end-of-lifed in > the not-too-distant future, I decided to go with 5.1. > > Personally, I would only go with 4.8 if testing showed 5.1 to be > inadequate for your particular situation with your particular apps, > hardware, load, etc. But you can only tell that by testing. Glad to hear that 5.1 is getting used in the work place. Were there any places where your testing showed huge gaps in performance? -sc -- Sean Chittenden