From owner-freebsd-questions@freebsd.org Wed Aug 26 21:18:31 2015 Return-Path: Delivered-To: freebsd-questions@mailman.ysv.freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:1900:2254:206a::19:1]) by mailman.ysv.freebsd.org (Postfix) with ESMTP id 5FA7E9C27D6 for ; Wed, 26 Aug 2015 21:18:31 +0000 (UTC) (envelope-from kudzu@tenebras.com) Received: from mail-qk0-f182.google.com (mail-qk0-f182.google.com [209.85.220.182]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (Client CN "smtp.gmail.com", Issuer "Google Internet Authority G2" (verified OK)) by mx1.freebsd.org (Postfix) with ESMTPS id 22F571093 for ; Wed, 26 Aug 2015 21:18:30 +0000 (UTC) (envelope-from kudzu@tenebras.com) Received: by qkda128 with SMTP id a128so77780476qkd.3 for ; Wed, 26 Aug 2015 14:18:24 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20130820; h=x-gm-message-state:mime-version:in-reply-to:references:date :message-id:subject:from:to:cc:content-type; bh=jaH/IZ/NLy8HmMvMZU8ZYYpdYQ8NO6kZPrxaQOk6C38=; b=eBoED4o8452vnwWN9PoiyCgZQXndSQ8ah6OfqENRLDDgdb/1HcsWs+oUryER/phmmr k0ItNMsD/ZhmU0TyfAJQebWpw8v9HOkz6Zyn/qU879LXVsvedvEgZnV2miLenhsJK+mE WWAqF7I4rRgINBmBuhzo2Y30v57VtM27ct7eW0r+pAydbzb/lkHBVylT3kBHWJSP5/H+ ZCPOjAEdz0o2tkWEesNJGZ30kajvS4LwrQDOy+hXtyz7IM3aUj4ZMhCJfph29fp2gC2k kxzcCNrWrKfZdCWpJG/foLplqJ5/vUkW+fH5Z+lSO9o/9jO389uhu1fHjHSA9zpdKNVb jF3A== X-Gm-Message-State: ALoCoQkfok4C/Q4j4VoNGAzlZ8eFV/kqql6ligUlUA/VcrcG9Ard0qAHzhiqUWfzEWcq5mCZJIQZ MIME-Version: 1.0 X-Received: by 10.55.21.40 with SMTP id f40mr1014810qkh.57.1440623904174; Wed, 26 Aug 2015 14:18:24 -0700 (PDT) Received: by 10.140.41.230 with HTTP; Wed, 26 Aug 2015 14:18:23 -0700 (PDT) In-Reply-To: References: <1440496718919-6034932.post@n5.nabble.com> <55DC3FBD.8080102@FreeBSD.org> <1440500542763-6034941.post@n5.nabble.com> <55DC53A8.3020508@FreeBSD.org> <55DC55AD.9070209@FreeBSD.org> Date: Wed, 26 Aug 2015 14:18:23 -0700 Message-ID: Subject: Re: How to minimize the number of writes to CF card? From: Michael Sierchio To: Christian Weisgerber Cc: FreeBSD Questions Content-Type: text/plain; charset=UTF-8 X-Content-Filtered-By: Mailman/MimeDel 2.1.20 X-BeenThere: freebsd-questions@freebsd.org X-Mailman-Version: 2.1.20 Precedence: list List-Id: User questions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Wed, 26 Aug 2015 21:18:31 -0000 On Wed, Aug 26, 2015 at 1:57 PM, Christian Weisgerber wrote: > On 2015-08-25, Matthew Seaman wrote: > > > However, I don't think softupdates has much effect on the /number/ or > > writes made to the filesystem. It's all about re-ordering writes to > > ensure metadata consistency. > > Time to re-read Kirk's original paper. > > http://www.usenix.org/publications/library/proceedings/usenix99/full_papers/mckusick/mckusick.pdf > > See section 5. Choice quote: > > "Overall, 4.4BSD systems tend to require 40 percent fewer disk > writes and complete tasks 25 percent more quickly than when using > the default 4.4BSD fast filesystem implementation." > > At a cost, including the fact that unlink and other directory operations are not atomic - eventual consistency is promised. - M