Date: Wed, 7 Nov 2007 04:17:06 -0800 (PST) From: Arne "Wörner" <arne_woerner@yahoo.com> To: Ivan Voras <ivoras@freebsd.org>, freebsd-current@freebsd.org Subject: Re: geom_raid5 inclusion in HEAD? Message-ID: <487375.1457.qm@web30309.mail.mud.yahoo.com> In-Reply-To: <fgs516$mj8$1@ger.gmane.org>
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--- Ivan Voras <ivoras@freebsd.org> wrote: > Arne Wörner wrote: > I don't remember entire discussions about geom_raid5 but I seem to > recall there was concern about its aggressive caching, possibly in the > write path, which could make recovery in case of e.g. power outage > problematic. I'm possibly mis-remembering this so feel free to ignore if > it's not relevant to your geom_raid5. > graid5 puts write requests for about kern.geom.raid5.wdt seconds (but not less than 1-2 seconds) into the write cache (if there is enough space left in graid5's write cache)... I would guess that this behaviour is pretty incompatible with soft-updates with power outage... Then there still is the write cache of the hard discs (I dont know how long it waits, but that time would come in addition to graid5's delay)... Maybe gjournal could help, because graid5 honors the BIO_FLUSH, but that is untested... -Arne __________________________________________________ Do You Yahoo!? Tired of spam? Yahoo! Mail has the best spam protection around http://mail.yahoo.com
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