Date: Sat, 16 Jul 2005 17:32:03 -0700 (PDT) From: Jon Dama <jd@ugcs.caltech.edu> To: Matthias Buelow <mkb@incubus.de> Cc: freebsd-stable@freebsd.org, Lowell Gilbert <freebsd-stable-local@be-well.ilk.org> Subject: Re: dangerous situation with shutdown process Message-ID: <Pine.LNX.4.53.0507161727530.15102@vomit.ugcs.caltech.edu> In-Reply-To: <20050716172632.GG752@drjekyll.mkbuelow.net> References: <20050715224650.GA48516@outcold.yadt.co.uk> <200507152342.j6FNg5Tx015427@drjekyll.mkbuelow.net> <20050716133710.GA71580@outcold.yadt.co.uk> <20050716141630.GB752@drjekyll.mkbuelow.net> <1121530912.17757.32.camel@zappa.Chelsea-Ct.Org> <44k6jqof72.fsf@be-well.ilk.org> <20050716172632.GG752@drjekyll.mkbuelow.net>
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No, it's at a level below softupdates that this must be done. Softupdates only understands when things have been marked completed with biodone()--the underlying scsi/ata/sata driver must make the determination as to when biodone should be called. The flush has to be done there. _IF_ the flush is being done there, then request barriers represent a performance enhancement, not an integrity enhancement. -Jon On Sat, 16 Jul 2005, Matthias Buelow wrote: > Lowell Gilbert wrote: > > >Well, break it down a little bit. If an ATA drive properly implements > >the cache flush command, then none of the ongoing discussion is > > Are you sure this is the case? Are there sequence points in softupdates > where it issues a flush request and by this guarantees fs integrity? > I've read thru McKusick's paper in search for an answer but haven't > found any. All I've read so far on mailing lists and from googling > was that softupdates doesn't work if the wb-cache is enabled. > > mkb. > _______________________________________________ > freebsd-stable@freebsd.org mailing list > http://lists.freebsd.org/mailman/listinfo/freebsd-stable > To unsubscribe, send any mail to "freebsd-stable-unsubscribe@freebsd.org" >
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