Date: Sun, 22 Feb 2004 17:23:15 +0100 From: Gabriel Ambuehl <gabriel_ambuehl@buz.ch> To: Heinrich Rebehn <rebehn@ant.uni-bremen.de> Cc: questions@freebsd.org Subject: Re[2]: UNEXPECTED SOFTUPDATES INCONSISTENCY Message-ID: <1693129206.20040222172315@buz.ch> In-Reply-To: <4038D21B.2030903@ant.uni-bremen.de> 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>
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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
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