On Wed, Sep 13, 2006 at 05:28:49PM +0200, Teufel wrote: > Pawel Jakub Dawidek wrote: > >>>- todays desktop drives can lie about writing data. SoftUpdates relies > >>>on some assumptions about when the data is physically written to > >>>media, and those are not always valid today > >>> > >>I think journaling relies on the same assumptions. > >> > > > >Not gjournal, because it uses BIO_FLUSH I/O requests which flushes disk > >write cache when needed > so when the crash occur exactly when BIO_FLUSH is sent or while the > cache is flushing, there is still no corruption possbile? [...]
That's right. One BIO_FLUSH is send to ensure the data are safely stored, and another one is send when metadata is updated to point at the last consistent journal. > [...] If so, this would be an advantage over SU, as > it does surely not use the new introduced BIO_FLUSH. [...] Soft-updates doesn't handle disk write caches at all. > [...] In the other hand i've seen couple of other JFS that went corrupt for > "no reason". I don't want to be paranoid, but i > really want to be "sure" that the design is trustable. Of course a bug in file system (or gjournal) implementation is still possible and can lead to file system corruption, but such a bug can still corrupt file system in the way it will not be fixable by fsck. From what I saw, file systems with journaling still enforce fsck every X reboots or on the next reboot after Y days of uptime, whatever comes first. -- Pawel Jakub Dawidek http://www.wheel.pl [EMAIL PROTECTED] http://www.FreeBSD.org FreeBSD committer Am I Evil? Yes, I Am!
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