Date: Wed, 26 Aug 2015 14:18:23 -0700 From: Michael Sierchio <kudzu@tenebras.com> To: Christian Weisgerber <naddy@mips.inka.de> Cc: FreeBSD Questions <freebsd-questions@freebsd.org> Subject: Re: How to minimize the number of writes to CF card? Message-ID: <CAHu1Y72Li_%2BkV%2BywfxLJH=Jy4c6hLcsbrt7zxB8fe2YeeiKZ%2BQ@mail.gmail.com> In-Reply-To: <slrnmtsa1p.2cu3.naddy@lorvorc.mips.inka.de> 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> <slrnmtsa1p.2cu3.naddy@lorvorc.mips.inka.de>
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On Wed, Aug 26, 2015 at 1:57 PM, Christian Weisgerber <naddy@mips.inka.de> wrote: > On 2015-08-25, Matthew Seaman <matthew@FreeBSD.org> 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
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