Date: Fri, 7 Dec 2001 01:26:15 +0000 (UTC) From: naddy@mips.inka.de (Christian Weisgerber) To: freebsd-questions@freebsd.org Subject: Re: Journaling File Systems and Soft Updates confusion Message-ID: <9up5rn$2l3v$1@kemoauc.mips.inka.de> References: <63ba6e639af8.639af863ba6e@mbox.com.au>
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BSD Freak <bsd-freak@mbox.com.au> 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
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