From owner-freebsd-current@FreeBSD.ORG Wed Nov 7 12:17:15 2007 Return-Path: Delivered-To: freebsd-current@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34]) by hub.freebsd.org (Postfix) with ESMTP id C097916A419 for ; Wed, 7 Nov 2007 12:17:15 +0000 (UTC) (envelope-from arne_woerner@yahoo.com) Received: from web30309.mail.mud.yahoo.com (web30309.mail.mud.yahoo.com [209.191.69.71]) by mx1.freebsd.org (Postfix) with SMTP id 72FFB13C4D9 for ; Wed, 7 Nov 2007 12:17:14 +0000 (UTC) (envelope-from arne_woerner@yahoo.com) Received: (qmail 1927 invoked by uid 60001); 7 Nov 2007 12:17:06 -0000 DomainKey-Signature: a=rsa-sha1; q=dns; c=nofws; s=s1024; d=yahoo.com; h=X-YMail-OSG:Received:Date:From:Subject:To:In-Reply-To:MIME-Version:Content-Type:Content-Transfer-Encoding:Message-ID; b=1rLTVS70JKyBgrtejcaU+km73rDSNcV+aEUWCd++ia2/gkRaCloR58YXuoao2I3NDRaMpOUD8CzHtGNCU28f2oeui02Q53BGAeOWzzBP7hDyi31cccOv0sd1yd5+QzrJTUvqeJWtzzpUvEEqzKKuO1y16ePfcETFypP/8Hf05+4=; X-YMail-OSG: hX1QpBoVM1kjvOup_0RoJ8uXG1s3CvmhwmkXnO5587JiteKx4NkBNm50EyWMtvf6mZx1hQvsRtOwjeRFkWOGTul1VWMfzkBLZH4PbdkzZwQNHNzIq2U- Received: from [84.141.120.234] by web30309.mail.mud.yahoo.com via HTTP; Wed, 07 Nov 2007 04:17:06 PST Date: Wed, 7 Nov 2007 04:17:06 -0800 (PST) From: Arne "Wörner" To: Ivan Voras , freebsd-current@freebsd.org In-Reply-To: MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Transfer-Encoding: 8bit Message-ID: <487375.1457.qm@web30309.mail.mud.yahoo.com> Cc: Subject: Re: geom_raid5 inclusion in HEAD? X-BeenThere: freebsd-current@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: Discussions about the use of FreeBSD-current List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Wed, 07 Nov 2007 12:17:15 -0000 --- Ivan Voras 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