From owner-freebsd-questions Thu Dec 6 17:30:34 2001 Delivered-To: freebsd-questions@freebsd.org Received: from mail.inka.de (quechua.inka.de [212.227.14.2]) by hub.freebsd.org (Postfix) with ESMTP id E2A1537B416 for ; Thu, 6 Dec 2001 17:30:29 -0800 (PST) Received: from kemoauc.mips.inka.de (uucp@) by mail.inka.de with local-bsmtp id 16C9qO-00002N-01; Fri, 7 Dec 2001 02:30:28 +0100 Received: (from daemon@localhost) by kemoauc.mips.inka.de (8.11.6/8.11.6) id fB71QFk87176 for freebsd-questions@freebsd.org; Fri, 7 Dec 2001 02:26:15 +0100 (CET) (envelope-from daemon) From: naddy@mips.inka.de (Christian Weisgerber) Subject: Re: Journaling File Systems and Soft Updates confusion Date: Fri, 7 Dec 2001 01:26:15 +0000 (UTC) Message-ID: <9up5rn$2l3v$1@kemoauc.mips.inka.de> References: <63ba6e639af8.639af863ba6e@mbox.com.au> Originator: naddy@mips.inka.de (Christian Weisgerber) To: freebsd-questions@freebsd.org Sender: owner-freebsd-questions@FreeBSD.ORG Precedence: bulk List-ID: List-Archive: (Web Archive) List-Help: (List Instructions) List-Subscribe: List-Unsubscribe: X-Loop: FreeBSD.ORG BSD Freak wrote: > I have read several articles on the issue and spoken to a few people > regarding this issue and when ever I mention a journaling file system > to FreeBSD people I automatically get pointed to Soft Updates as being > an equivalent. Yes. This is both valid to a certain degree and it is a knee-jerk reaction. > As far as I am aware this is not case at all. Depends on what your goals are. I highly recommend this paper, which compares various approaches to guaranteeing meta-data consistency: http://www.usenix.org/publications/library/proceedings/usenix2000/general/seltzer.html When reading this, you should notice that there are many aspects involved and that there are several types of "journaling". > The whole point of a journaling file system on systems such as > Linux/NT/Solaris etc. is not to increase performance but rather to > avoid an 'fsck' when the server gets shutdown "uncleanly". This may be the common perception of typical Linux users, but it is a complete misrepresentation. > FreeBSD's ffs curently cannot do this (avoid an fsck) with or without > soft updates. Actually, as any -CURRENT user can tell you, the combination of softupdates and snapshots allows background filesystem checks (which really only free some blocks mistakenly still marked as allocated). -- Christian "naddy" Weisgerber naddy@mips.inka.de To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-questions" in the body of the message