Date: Tue, 13 Mar 2001 04:04:38 +0000 (GMT) From: Terry Lambert <tlambert@primenet.com> To: mjacob@feral.com Cc: bright@wintelcom.net (Alfred Perlstein), gibbs@scsiguy.com (Justin T. Gibbs), sos@freebsd.dk (Soren Schmidt), oberman@es.net (Kevin Oberman), scsi@FreeBSD.ORG, fs@FreeBSD.ORG, dillon@FreeBSD.ORG Subject: Re: Disk I/O problem in 4.3-BETA Message-ID: <200103130404.VAA03536@usr05.primenet.com> In-Reply-To: <Pine.LNX.4.21.0103121546290.31161-100000@zeppo.feral.com> from "Matthew Jacob" at Mar 12, 2001 03:53:10 PM
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> > Afaik we never depend on actually B_ORDERED'd data, at least not > > for filesystem consistancy (as afaik it would violate USL patents). > > Hmm? Wasn't there an assertion about this from Terry IIRC? Huh.. as far as I > remember Steve Kleiman was talking about this at Sun in 1990- dunno if this > has any pertinence to the patent or usage. Depends on how you use them; the actual assignee was Novell; I got to see the filing materials back in 1993, when I was a Novell/USG (former USL, from the Novell side) attributed FS guru; see: US5642501:Computer method and apparatus for asynchronous ordered operations http://www.delphion.com/details?pn=US05642501__ US5666532:Computer method and apparatus for asynchronous ordered operations http://www.delphion.com/details?pn=US05666532__ Be warned; they are 175 and 34 pages, respectively. > Did I misunderstand your questions to Justin? It's quite possible as I've been > switching between 5 different systems I'm working on today and I'm sure that > things didn't committed to &my& media before things were wiped as switched > from one KDE desktop to another..... I think Alfred just wants them to be forced to stable storage before a dependency is considered statisfied; if so, there's no patent issue with D.O.W. (Delayed Ordered Writes). There might be an issue with one of the claims in the first patent, if you were to do write gathering, like Alfred had suggested. Doing that would be a mistake anyway: you might as well mount the thing async if you are going to write cache dependencies such that they aren't committed in the correct order, and a partial commit would then be possible. Terry Lambert terry@lambert.org --- Any opinions in this posting are my own and not those of my present or previous employers. To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-fs" in the body of the message
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