From owner-freebsd-questions@FreeBSD.ORG Fri Mar 31 05:50:55 2006 Return-Path: X-Original-To: freebsd-questions@freebsd.org Delivered-To: freebsd-questions@freebsd.org Received: from mx1.FreeBSD.org (mx1.freebsd.org [216.136.204.125]) by hub.freebsd.org (Postfix) with ESMTP id 24E9D16A400 for ; Fri, 31 Mar 2006 05:50:55 +0000 (UTC) (envelope-from usleepless@gmail.com) Received: from zproxy.gmail.com (zproxy.gmail.com [64.233.162.201]) by mx1.FreeBSD.org (Postfix) with ESMTP id 8232243D49 for ; Fri, 31 Mar 2006 05:50:54 +0000 (GMT) (envelope-from usleepless@gmail.com) Received: by zproxy.gmail.com with SMTP id l8so691581nzf for ; Thu, 30 Mar 2006 21:50:54 -0800 (PST) DomainKey-Signature: a=rsa-sha1; q=dns; c=nofws; s=beta; d=gmail.com; h=received:message-id:date:from:to:subject:cc:in-reply-to:mime-version:content-type:content-transfer-encoding:content-disposition:references; b=p5GPTt6Vjw0ONVI5U6ItpEs4GnxZi7YwKr/O5+Etwem3+/9Kl/K+Ui1mlTKGJ0p2aIfFIWpyEFwpojDj+L9rTOMvnphTDqC98EmyAqn4GeUT/SiHxxkyJfuZ461rJSTTL8CidWd9yehNh+AsSZMTGn9ZIPK0YFlBM5BPLwIKYcw= Received: by 10.36.250.70 with SMTP id x70mr152602nzh; Thu, 30 Mar 2006 21:50:53 -0800 (PST) Received: by 10.36.154.7 with HTTP; Thu, 30 Mar 2006 21:50:53 -0800 (PST) Message-ID: Date: Fri, 31 Mar 2006 07:50:53 +0200 From: usleepless@gmail.com To: "Bill Moran" In-Reply-To: <20060330192437.043e88ff.wmoran@collaborativefusion.com> MIME-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: quoted-printable Content-Disposition: inline References: <442B2FC6.9040001@123.com.sv> <20060330011834.GA84658@xor.obsecurity.org> <442BF0BB.8010504@123.com.sv> <20060330202145.GA17856@xor.obsecurity.org> <20060330205858.GA21147@xor.obsecurity.org> <20060330192437.043e88ff.wmoran@collaborativefusion.com> Cc: mmiranda@123.com.sv, freebsd-questions@freebsd.org, Kris Kennaway Subject: Re: terrible performance in 6.1beta4 X-BeenThere: freebsd-questions@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: User questions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Fri, 31 Mar 2006 05:50:55 -0000 Bill, > > Actually I seem to recall that on Linux with default settings fsync() > > lies and does not actually sync data before returning, so maybe it's > > worth turning off on FreeBSD too if you're comfortable with the > > implications of this. > > If you have fsync off and the system crashes, your PostgreSQL database > will probably be corrupt beyond repair. that is not true. that is not "probable", at least, it never happened to me. and i encountered some panics over the last months ( i have been patching multimedia/pvr250 to support 500s ). in fact, PostgreSQL never corrupted on me in 5 years ( i used to use to mysql, which seemed to corrupt by looking at it ). however, i am not in the large number of transactions-business. there is a sustained number of updates though, at least once every 2 minutes. > I believe the official word from the PostgreSQL folks is that fsync is > safe to turn off if you've got battery-backed cache on your disk > controllers. Many high-end SCSI controllers have this as an option. interesting, i didn't know. > Alternatively, if you're just putting the database on for the first > time, you can temporarily turn fsync off while you're uploading the > data. If the system crashes during this, just delete and recreate > the database and try again. my suggestion to turn fsync of was geared towards this particular problem, although i did not explicitly state that. it is a good thing you are pointing out potential problems. > It's not generally a good idea to run in production with fsync off, > however, unless you have a battery on your controller. While you might be very right, my server only has an UPS, and i am comfortable with that given the stability of FBSD. regards, usleep > > -- > Bill Moran > Potential Technologies > http://www.potentialtech.com >