From owner-freebsd-current@FreeBSD.ORG Sat Jan 9 09:53:09 2010 Return-Path: Delivered-To: freebsd-current@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34]) by hub.freebsd.org (Postfix) with ESMTP id A68C21065670 for ; Sat, 9 Jan 2010 09:53:09 +0000 (UTC) (envelope-from mavbsd@gmail.com) Received: from mail-fx0-f227.google.com (mail-fx0-f227.google.com [209.85.220.227]) by mx1.freebsd.org (Postfix) with ESMTP id 34FE18FC0C for ; Sat, 9 Jan 2010 09:53:08 +0000 (UTC) Received: by fxm27 with SMTP id 27so5346200fxm.3 for ; Sat, 09 Jan 2010 01:53:03 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=gamma; h=domainkey-signature:received:received:sender:message-id:date:from :user-agent:mime-version:to:cc:subject:references:in-reply-to :content-type:content-transfer-encoding; bh=2STK7SVXrMsOlYQCUv2yar6xO4KQX1tI2FA+9EcsRo4=; b=nU3GlpTsQ6IMvN1cCvYP6CmF70sK10ccbo3M1BxlUUpA4zvJe/OaQcmiOqYVAfiGsC v4m9S5t3huiSG4CINQF0z0v3EpzSkrpM1ZFmeWILCkLEkr1GUHG5FPOnVI2Hw0XLn+QK Hvz647H6ZgckGy2urnoI7Z+Az9GTuZG+2NRZ8= DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=sender:message-id:date:from:user-agent:mime-version:to:cc:subject :references:in-reply-to:content-type:content-transfer-encoding; b=mC1pE8Kn6dOCyVqfVSRtqPCeEzR+ty3fAnyTFeaeF68ZqQiHWfX2pJDemUIZ3rh+kN XNcPHaSc/p3p8OW7E53PKdHB+MyhFn0BlYGvixAozbX4LFFjeSw1sVFH4PAmGqFW3Jca HQaDswlhuOKdXZdVoZm9MWamVi7j97eTfxeSQ= Received: by 10.223.18.137 with SMTP id w9mr4084335faa.61.1263030783578; Sat, 09 Jan 2010 01:53:03 -0800 (PST) Received: from mavbook.mavhome.dp.ua (pc.mavhome.dp.ua [212.86.226.226]) by mx.google.com with ESMTPS id 15sm8654301fxm.10.2010.01.09.01.53.02 (version=SSLv3 cipher=RC4-MD5); Sat, 09 Jan 2010 01:53:02 -0800 (PST) Sender: Alexander Motin Message-ID: <4B4851FE.2020907@FreeBSD.org> Date: Sat, 09 Jan 2010 11:53:02 +0200 From: Alexander Motin User-Agent: Thunderbird 2.0.0.23 (X11/20091212) MIME-Version: 1.0 To: Jeff Roberson References: In-Reply-To: Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Cc: FreeBSD-Current Subject: Re: Help test softupdates journaling (SUJ) X-BeenThere: freebsd-current@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: Discussions about the use of FreeBSD-current List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Sat, 09 Jan 2010 09:53:09 -0000 Hi. Jeff Roberson wrote: > I have been augmenting softupdates with a small journal that will be > processed in lieu of fsck in the event of a crash. I have written some > about this project here: http://jeffr_tech.livejournal.com/ Sounds cool, but I have one question. Excuse my possible ignorance. I was looking for BIO_FLUSH consumers and haven't found UFS there. Unbacked write caching probably can make SoftUpdates unreliable, but it is bearable while foreground fsck is used. As I understand, journaled recovery is more dependent on data coherency, and so needs either unbacked write caching to be disabled, or BIO_FLUSH to be used in respective points by FS code. Am I right? So what's about BIO_FLUSH? -- Alexander Motin