Date: Mon, 12 Mar 2001 16:07:43 -0800 From: Alfred Perlstein <bright@wintelcom.net> To: Matthew Jacob <mjacob@feral.com> Cc: "Justin T. Gibbs" <gibbs@scsiguy.com>, Soren Schmidt <sos@freebsd.dk>, Kevin Oberman <oberman@es.net>, scsi@FreeBSD.ORG, fs@FreeBSD.ORG, dillon@FreeBSD.ORG Subject: Re: Disk I/O problem in 4.3-BETA Message-ID: <20010312160742.L18351@fw.wintelcom.net> In-Reply-To: <Pine.LNX.4.21.0103121546290.31161-100000@zeppo.feral.com>; from mjacob@feral.com on Mon, Mar 12, 2001 at 03:53:10PM -0800 References: <20010312154452.K18351@fw.wintelcom.net> <Pine.LNX.4.21.0103121546290.31161-100000@zeppo.feral.com>
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* Matthew Jacob <mjacob@feral.com> [010312 15:53] wrote: > > > If you need everything sync'd, you'll have to explicitly have the da driver > > > send the SYNCHRONIZE CACHE command. > > > > 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. > > > We really don't need the SYNCHRONIZE CACHE either, basically a B_FLUSH > > would be nice, the problem I see is making sure it doesn't get eaten > > by the millions :) of OR's and AND's on the b_flags fields. > > Well, if I understood your mail, you were trying to find out a way to live > safely with not only ordering (which is done in s/w with softupdates for > FreeBSD, right?- last I heard from Steve Tweedie was that he was considering > using tags for ordering in ext3) but also to try and live safely with data > that is cached on the drive electronics but not committed to media yet. > > 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..... Your previous paragraph "Well, if I understood your mail" is what I was looking for. Basically I was inquiring if the hardware could/would support a request to perform a write-through or not lie about the write completing for certain tagged writes. -- -Alfred Perlstein - [bright@wintelcom.net|alfred@freebsd.org] Daemon News Magazine in your snail-mail! http://magazine.daemonnews.org/ To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-fs" in the body of the message
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