Date: Fri, 26 Aug 2016 10:46:17 -0500 From: Linda Kateley <lkateley@kateley.com> To: freebsd-fs@freebsd.org Subject: Re: [ZFS] ARC accounting bug ? Message-ID: <453b967d-4139-c6b6-a27a-223ed4d92c74@kateley.com> In-Reply-To: <9A3B2699-B077-4F72-90A5-63D7E22BE652@gmail.com> References: <C2642B73-83F2-4A1C-88BE-322F376861FF@gmail.com> <5B8C6663-5D21-4C03-AC69-CB7E70D3A6C2@gmail.com> <067ac0ed-1f2d-c9fb-de4d-ed5da62fe10c@internetx.com> <9EAAEEC5-0FFF-474D-9AD0-4447CD6B549B@gmail.com> <c45b36de-b43f-6eae-4187-142f1e5c3e48@internetx.com> <91665D7B-D2EA-4A7F-BE8D-67BE238DAF6B@gmail.com> <9A3B2699-B077-4F72-90A5-63D7E22BE652@gmail.com>
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Metadata updates when you access a file. Atime is most often updated and you will miss. If you are running vm's on zfs I always recommend to turn off atime updates. Metadata is usually tiny so you probably won't see disk activity On 8/26/16 10:27 AM, Ben RUBSON wrote: > I'm sorry but I still can't find out where do these ARC demand metadata misses come from. > In addition, why they are not cached, as my ARC is 1% used. > And why I don't see any disk activity to honour them. > > I would really be glad if you could enlighten me :) > > Many thanks again, > > Ben > > > >> On 26 Aug 2016, at 14:28, Ben RUBSON <ben.rubson@gmail.com> wrote: >> >> Yes Juergen, metadata only stores in ARC files' info (location in pool and some other useful info), not the user data. >> >> I think "find" only needs metadata, as it does not read the files' content. >> Which can be "verified" because : >> - there is no IO at all on the pool (after the first find loop, once ARC has the needed metadata) ; >> - there is no ARC demand data at all. >> But I may be wrong, so of course feel free to correct me. Thank you. >> >> Thank you for the links, I already read them before posting here, but I may have missed something. >> >> Ben >> >>> On 26 Aug 2016, at 14:16, InterNetX - Juergen Gotteswinter <juergen.gotteswinter@internetx.com> wrote: >>> >>> so, you know the difference between >>> >>> - metadata >>> - data >>> >>> ? >>> >>> if yes, what is your find actually doing in this case? >>> >>> regarding arc >>> >>> http://dtrace.org/blogs/brendan/2012/01/09/activity-of-the-zfs-arc/ >>> https://www.patpro.net/blog/index.php/2014/03/19/2628-zfs-primarycache-all-versus-metadata/ >>> >>> >>> >>> Am 26.08.2016 um 14:06 schrieb Ben RUBSON: >>>> Juergen, thank you for your answer. >>>> So where do you think these ARC misses come from ? I can't find out :S >>>> Thank you ! >>>> >>>>> On 26 Aug 2016, at 14:01, InterNetX - Juergen Gotteswinter <juergen.gotteswinter@internetx.com> wrote: >>>>> >>>>> no bug, everything like i whould expect >>>>> >>>>> Am 26.08.2016 um 11:40 schrieb Ben RUBSON: >>>>>> uname -v >>>>>> FreeBSD 11.0-RC2 #0 r304729: Wed Aug 24 06:59:03 UTC 2016 root@releng2.nyi.freebsd.org:/usr/obj/usr/src/sys/GENERIC > _______________________________________________ > freebsd-fs@freebsd.org mailing list > https://lists.freebsd.org/mailman/listinfo/freebsd-fs > To unsubscribe, send any mail to "freebsd-fs-unsubscribe@freebsd.org"
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