Date: Thu, 26 Sep 2002 21:59:51 +0200 From: Matthias Schuendehuette <msch@snafu.de> To: freebsd-current@freebsd.org Subject: Re: Journaled filesystem in CURRENT Message-ID: <200209262159.51470.msch@snafu.de>
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Terry Lambert wrote: > Yes, soft updates does nothing of user data, it is a metadata > technology. Journalling is implementation dependent; not all > JFS implementations will journal data which is not metadata, so > your results would depend on the JFS. I think you are not correct here. If I understand Kirks paper right, Soft Updates do a sorting/nesting of data and metadata within the buffer cache. My knowledge is, that most of the journaling implementations do metadata journaling and do not guarantee data consistency (ext3 with data=journal is the only exception I know of), whereas SU *does* guarantee data consistency (admittedly with a time lag) because of that nesting from data with metadata. I'm far away from beeing able to follow this discussion in every detail, but please correct me if I'm wrong... -- Ciao/BSD - Matthias Matthias Schuendehuette <msch [at] snafu.de>, Berlin (Germany) Powered by FreeBSD 4.7-RC To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-current" in the body of the message
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