From owner-freebsd-questions@FreeBSD.ORG Sun Feb 22 10:08:19 2004 Return-Path: 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 60C1116A4CE for ; Sun, 22 Feb 2004 10:08:19 -0800 (PST) Received: from iota.root-servers.ch (iota.root-servers.ch [193.41.193.195]) by mx1.FreeBSD.org (Postfix) with SMTP id 6E36843D1F for ; Sun, 22 Feb 2004 10:08:18 -0800 (PST) (envelope-from gabriel_ambuehl@buz.ch) Received: (qmail 14679 invoked from network); 22 Feb 2004 16:21:18 -0000 Received: from 217-162-134-28.dclient.hispeed.ch (HELO ?10.2.2.3?) (217.162.134.28) by 0 with SMTP; 22 Feb 2004 16:21:18 -0000 Date: Sun, 22 Feb 2004 17:23:15 +0100 From: Gabriel Ambuehl Organization: BUZ Internet Services X-Priority: 3 (Normal) Message-ID: <1693129206.20040222172315@buz.ch> To: Heinrich Rebehn In-Reply-To: <4038D21B.2030903@ant.uni-bremen.de> References: <4037A0BB.8030807@ant.uni-bremen.de> <44n07c85md.fsf@be-well.ilk.org> <40388FF1.4000004@ant.uni-bremen.de> <1664802739.20040222113449@buz.ch> <4038D21B.2030903@ant.uni-bremen.de> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit cc: questions@freebsd.org Subject: Re[2]: UNEXPECTED SOFTUPDATES INCONSISTENCY X-BeenThere: freebsd-questions@freebsd.org X-Mailman-Version: 2.1.1 Precedence: list Reply-To: gabriel_ambuehl@buz.ch List-Id: User questions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Sun, 22 Feb 2004 18:08:19 -0000 Hello Heinrich, Sunday, February 22, 2004, 5:00:27 PM, you wrote: > Why that? I can imagine that i lose data in case of a power failure, but > why in case of a crash? Well I guess the card COULD still commit the data, however, who knows if it actually does it? > And why is write cache only dangerous with softupdates, as you wrote above? IIRC softupdates relies on the assumption that when the softupdate changes return, they really ARE on the disk. It's the same with most RDBMS: because they go to great lengths to ensure the journal is in an ok state they need to know for sure that the data they wrote to it actually made it to disk. > Since i found no word about disabling write cache in the FreeBSD > handbook or in man tuning(7), i would really like to know, if this is > just a rumour, or where does it come from? I can't say for sure, but I have little confidence in write caching anyhow. It changes semantics the system relies on, for one. Best regards, Gabriel