From owner-freebsd-questions@FreeBSD.ORG Sat Dec 2 00:12:06 2006 Return-Path: X-Original-To: freebsd-questions@freebsd.org Delivered-To: freebsd-questions@freebsd.org Received: from mx1.FreeBSD.org (mx1.freebsd.org [69.147.83.52]) by hub.freebsd.org (Postfix) with ESMTP id 111EC16A417 for ; Sat, 2 Dec 2006 00:12:06 +0000 (UTC) (envelope-from smurphy@calarts.edu) Received: from echo.calarts.edu (echo.calarts.edu [198.182.157.9]) by mx1.FreeBSD.org (Postfix) with ESMTP id CF65743C9D for ; Sat, 2 Dec 2006 00:11:48 +0000 (GMT) (envelope-from smurphy@calarts.edu) Received: from echo.calarts.edu (localhost.localdomain [127.0.0.1]) by localhost (Postfix) with SMTP id A40A1101E3E4 for ; Sat, 2 Dec 2006 00:08:02 +0000 (GMT) Received: from muse2.calarts.edu (muse2.calarts.edu [198.182.157.28]) by echo.calarts.edu (Postfix) with ESMTP id 9866F1018B27 for ; Sat, 2 Dec 2006 00:08:02 +0000 (GMT) Received: from [172.24.0.177] ([172.24.0.177]) (authenticated bits=0) by muse2.calarts.edu (8.13.3/8.13.3) with ESMTP id kB20C5TE094938 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=NOT) for ; Fri, 1 Dec 2006 16:12:05 -0800 (PST) (envelope-from smurphy@calarts.edu) Message-ID: <4570C4D6.5030708@calarts.edu> Date: Fri, 01 Dec 2006 16:12:06 -0800 From: Sean Murphy User-Agent: Thunderbird 1.5.0.8 (Windows/20061025) MIME-Version: 1.0 To: freebsd-questions@freebsd.org Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit X-Scanned-By: MIMEDefang 2.52 on 198.182.157.28 Subject: Soft Updates Help 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: Sat, 02 Dec 2006 00:12:06 -0000 I have read up on soft updates and have some questions. The way that I am understanding soft updates purpose is to allow file systems to be mounted dirty after an unclean shutdown of the system. This will allow fsck to run in the background to restore the consistency of the file system which is compared against a snapshot of the system. It also increases performance of heavily written file systems by waiting to write the metadata of files and directories until a more opportune time. I have questions about this. When is the snapshot taken, how often, do I have to do it or does a program or kernel do it? If this is a safe way to restore consistency why is it not used on /? If a file system is not heavily written to is it better not to use soft updates? How do I know when the background fsck is finished and if it was successful? Do I have to add anything to enable the backgound fsck? When file systems are mounted dirty and our being used while the backgound fsck is running on the file systems how does it prevent files from being lost? Thanks