Date: Sun, 22 Feb 2004 17:49:46 +0000 From: Heinrich Rebehn <rebehn@ant.uni-bremen.de> To: gabriel_ambuehl@buz.ch Cc: questions@freebsd.org Subject: Re: UNEXPECTED SOFTUPDATES INCONSISTENCY Message-ID: <4038EBBA.9030400@ant.uni-bremen.de> In-Reply-To: <1693129206.20040222172315@buz.ch> References: <4037A0BB.8030807@ant.uni-bremen.de> <44n07c85md.fsf@be-well.ilk.org> <40388FF1.4000004@ant.uni-bremen.de> <1664802739.20040222113449@buz.ch> <4038D21B.2030903@ant.uni-bremen.de> <1693129206.20040222172315@buz.ch>
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Gabriel Ambuehl wrote: > Hello Heinrich, > > Sunday, February 22, 2004, 5:00:27 PM, you wrote: > >>Why that? I can imagine that i lose data in case of a power failure, but >>why in case of a crash? > > > Well I guess the card COULD still commit the data, however, who knows > if it actually does it? > > >>And why is write cache only dangerous with softupdates, as you wrote above? > > > IIRC softupdates relies on the assumption that when the softupdate > changes return, they really ARE on the disk. It's the same with most > RDBMS: because they go to great lengths to ensure the journal is in an > ok state they need to know for sure that the data they wrote to it > actually made it to disk. > > >>Since i found no word about disabling write cache in the FreeBSD >>handbook or in man tuning(7), i would really like to know, if this is >>just a rumour, or where does it come from? > > > I can't say for sure, but I have little confidence in write caching > anyhow. It changes semantics the system relies on, for one. > > > > > Best regards, > Gabriel > Gabriel, what you write does make sense, although i really can't understand why this important info is not in the FreeBSD documentation. I have disabled write cache, but i will keep softupdates disabled as well for now, and see how the system behaves. Thanks for your help, Heinrich
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