ufs+softupdates / consistency

[Zhihui Zhang]

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 at 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 at freebsd.org mailing list
> http://lists.freebsd.org/mailman/listinfo/freebsd-fs
> To unsubscribe, send any mail to "freebsd-fs-unsubscribe at freebsd.org"
>=20