Date: Sun, 29 Oct 2000 20:46:38 -0800 From: "Crist J . Clark" <cjclark@reflexnet.net> To: Arun Sharma <adsharma@sharmas.dhs.org> Cc: freebsd-questions@FreeBSD.ORG Subject: Re: softupdates and (avoiding) fsck Message-ID: <20001029204638.A75251@149.211.6.64.reflexcom.com> In-Reply-To: <20001029191544.A27575@sharmas.dhs.org>; from adsharma@sharmas.dhs.org on Sun, Oct 29, 2000 at 07:15:44PM -0800 References: <20001029183443.A27388@sharmas.dhs.org> <20001029190021.Z75251@149.211.6.64.reflexcom.com> <20001029191544.A27575@sharmas.dhs.org>
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On Sun, Oct 29, 2000 at 07:15:44PM -0800, Arun Sharma wrote: > On Sun, Oct 29, 2000 at 07:00:21PM -0800, Crist J . Clark wrote: > > There is no way around fsck'ing when the system is brought down > > hard. (Not absolutely true, but you dowanna mount an unclean FS.) > > Soft updates does _NOT_ guarantee that you will come out of such a > > nasty thing without damage. It does make it much less likely, > > however. Carefully read, > > > > /usr/src/sys/ufs/ffs/README > > > > For more information on what soft updates really does. > > That file doesn't exist in -current anymore. But I found some other > file, which pointed me to: > > http://www.mckusick.com/softdep/ > > which says: > > > By ensuring that the only inconsistencies are unclaimed blocks or > > inodes, soft updates can eliminate the need to run a filesystem check > > program after every system crash. Instead, the system is brought up > > immediately. When it is convenient, a snapshot is taken and a background > > task can be run on on that snapshot to reclaim any lost blocks and > > inodes. The use of a snapshot allows normal filesystem activity to > > continue concurrently. Good you found the paper. Section 6 deals with the issue. Also, have a look at the fsck(8) source to see how it handles checking softupdate filesystems. -- Crist J. Clark cjclark@alum.mit.edu To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-questions" in the body of the message
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