Date: Mon, 27 May 2002 12:45:43 +0100 From: Kirk McKusick <mckusick@beastie.mckusick.com> To: Alfred Perlstein <bright@mu.org> Cc: fs@freebsd.org Subject: Re: softupdates durability enhancement? Message-ID: <200205271145.g4RBjhC00460@beastie.mckusick.com> In-Reply-To: Your message of "Fri, 08 Mar 2002 19:30:44 PST." <20020309033044.GC26621@elvis.mu.org>
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Date: Fri, 8 Mar 2002 19:30:44 -0800 From: Alfred Perlstein <bright@mu.org> To: mckusick@freebsd.org Cc: fs@freebsd.org Subject: softupdates durability enhancement? User-Agent: Mutt/1.3.27i People were complaining about crashes after softupdates giving them truncated files after reboot. I know from your earlier posts that this is actually more a bug in the way editors are prone to write out files than a real softupdates bug, I would also expect most logging filesystems to potentially have the same problem. One way to potentially reduce the chances of this are to more aggressively push out softdeps when the backlog is short. Meaning that when the softdep clock is nearly empty you push things out faster and as the clock fills with dependancies you begin to delay them up until the point you are forced to begin sync'ing them. The idea is for workstation loads where people are editing single files you reduce the window of having the file at zero length and thereby you protect them a bit more against stupid editors that do unsafe/non-transactionalsafe in-place updates. -- -Alfred Perlstein [alfred@freebsd.org] 'Instead of asking why a piece of software is using "1970s technology," start asking why software is ignoring 30 years of accumulated wisdom.' Tax deductible donations for FreeBSD: http://www.freebsdfoundation.org/ This suggestion seems reasonable. The hooks are already in place: kern.filedelay: 30 kern.dirdelay: 29 kern.metadelay: 28 Setting them to 1 would cause things to be sync'ed out 1-2 seconds after they were written. I am open to suggested heuristics for setting them to lower values. Kirk McKusick To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-fs" in the body of the message
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