Date: Wed, 26 Jan 2005 13:20:49 -0500 (EST) From: Zhihui Zhang <zzhang@cs.binghamton.edu> To: =?X-UNKNOWN?Q?Arne_W=F6rner?= <arne_woerner@yahoo.com> Cc: freebsd-fs@FreeBSD.ORG Subject: Re: ufs+softupdates / consistency Message-ID: <Pine.SOL.4.21.0501261317210.8299-100000@opal> In-Reply-To: <20050126174604.1701.qmail@web41205.mail.yahoo.com>
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No file system is super for ALL benchmarks. Maybe you should say something about your application, its access pattern, file count, file sizes, read/write ratio, etc. On Wed, 26 Jan 2005, Arne W=F6rner wrote: > --- David Schultz <das@FreeBSD.ORG> wrote: > > On Wed, Jan 26, 2005, Arne WXrner wrote: > > > On > > > http://e2fsprogs.sourceforge.net/ext2intro.html > > > I found the strings > > > "BSD-like synchronous updates" > > > "it can cause corruption in the user data" . > > > On > > > http://www.mckusick.com/softdep/ > > > I did not find such a statement. > > > Are soft updates safe for user data? I do not really > > > understand, what the first www page means... Maybe they mean, > > > that the new file size (that would be meta data, I think) is > > > written before the user data, so that the file contains > > > undetermined data in its tail. > >=20 > > The comments you refer to that seem to imply that synchronous > > updates are unsafe and asynchronous updates are safer are wrong > > in general (synchronous updates are safer), but the authors may > > be referring to bugs in the ext2fs implementation at that time. > > Soft Updates, in contrast, provides asynchronous updates, issued > > in an order that makes them safe. > >=20 > I would be glad, if somebody explains me, why ext2fs/async in > Linux kernel 2.4.27 (KNOPPIX V3.7) is much faster (about 4 times > faster) than a ufs with soft updates on the same slice of the hard > disc? >=20 > Is it due to consistency reasons? In case of a ext2fs/sync in my > Linux setting Linux was about 4 times slower. >=20 > Are we already trying to issue write order requests for the disc > blocks (whose write order is arbitrary) sorted by sector number > (in order to move the disc heads as less as possible)? The disc > write cache could do that, but I disabled it in order to decrease > the probability of inconsistency. >=20 > -Arne >=20 >=20 >=20 > =09=09 > __________________________________=20 > Do you Yahoo!?=20 > Yahoo! Mail - Find what you need with new enhanced search. > http://info.mail.yahoo.com/mail_250 > _______________________________________________ > freebsd-fs@freebsd.org mailing list > http://lists.freebsd.org/mailman/listinfo/freebsd-fs > To unsubscribe, send any mail to "freebsd-fs-unsubscribe@freebsd.org" >=20
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