Date: Fri, 10 May 2019 10:57:13 +1000 From: Michelle Sullivan <michelle@sorbs.net> To: Alan Somers <asomers@freebsd.org> Cc: Miroslav Lachman <000.fbsd@quip.cz>, FreeBSD-STABLE Mailing List <freebsd-stable@freebsd.org>, Dimitry Andric <dim@freebsd.org> Subject: Re: ZFS... Message-ID: <40021BE2-965B-4B37-969F-5391D5B931F7@sorbs.net> In-Reply-To: <CAOtMX2ip_G0afh_4AaYcQt4=zX4qkCTfs0qb66DpCgcALZXS5g@mail.gmail.com> References: <30506b3d-64fb-b327-94ae-d9da522f3a48@sorbs.net> <CAGMYy3tYqvrKgk2c==WTwrH03uTN1xQifPRNxXccMsRE1spaRA@mail.gmail.com> <5ED8BADE-7B2C-4B73-93BC-70739911C5E3@sorbs.net> <d0118f7e-7cfc-8bf1-308c-823bce088039@denninger.net> <2e4941bf-999a-7f16-f4fe-1a520f2187c0@sorbs.net> <20190430102024.E84286@mulder.mintsol.com> <41FA461B-40AE-4D34-B280-214B5C5868B5@punkt.de> <20190506080804.Y87441@mulder.mintsol.com> <08E46EBF-154F-4670-B411-482DCE6F395D@sorbs.net> <33D7EFC4-5C15-4FE0-970B-E6034EF80BEF@gromit.dlib.vt.edu> <A535026E-F9F6-4BBA-8287-87EFD02CF207@sorbs.net> <a82bfabe-a8c3-fd9a-55ec-52530d4eafff@denninger.net> <a1b78a63-0ef1-af51-4e33-a9a97a257c8b@sorbs.net> <CAMPTd_A7RYJ12pFyY4TzbXct82kWfr1hcEkSpDg7bjP25xjJGA@mail.gmail.com> <d91cf5@sorbs.net> <7D18A234-E7BF-4855-BD51-4AE2253DB1E4@sorbs.net> <E68600B3-F856-4909-AB6E-BDFCD8AAAB43@punkt.de> <805ee7f1-83f6-c59e-8107-4851ca9fce6e@quip.cz> <E980141F-48D9-4870-8FE1-9A5610F12826@FreeBSD.org> <5de7f3d3-b34c-0382-b7d4-b7e38339649b@quip>
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Michelle Sullivan http://www.mhix.org/ Sent from my iPad > On 09 May 2019, at 22:50, Alan Somers <asomers@freebsd.org> wrote: >=20 >> On Thu, May 9, 2019 at 5:37 AM Miroslav Lachman <000.fbsd@quip.cz> wrote:= >>=20 >> Dimitry Andric wrote on 2019/05/09 13:02: >>> On 9 May 2019, at 10:32, Miroslav Lachman <000.fbsd@quip.cz> wrote: >>=20 >> [...] >>=20 >>>> Disks are OK, monitored by smartmontools. There is nothing odd, just th= e long long scrubs. This machine was started with 4x 1TB (now 4x 4TB) and sc= rub was slow with 1TB disks too. This machine - HP ML110 G8) was my first ma= chine with ZFS. If I remember it well it was FreeBSD 7.0, now running 11.2. S= crub was / is always about one week. (I tried some sysctl tuning without muc= h gain) >>>=20 >>> Unfortunately https://svnweb.freebsd.org/changeset/base/339034, which >>> greatly speeds up scrubs and resilvers, was not in 11.2 (since it was >>> cut at r334458). >>>=20 >>> If you could update to a more recent snapshot, or try the upcoming 11.3 >>> prereleases, you will hopefully see much shorter scrub times. >>=20 >> Thank you. I will try 11-STABLE / 11.3-PRERELEASE soon and let you know >> about the difference. >>=20 >> Kind regards >> Miroslav Lachman >=20 > On 11.3 and even much older releases, you can greatly speed up scrub > and resilver by tweaking some sysctls. If you have spinning rust, > raise vfs.zfs.top_maxinflight so they'll do fewer seeks. I used to > set it to 8192 on machines with 32GB of RAM. Raising > vfs.zfs.resilver_min_time_ms to 5000 helps a little, too. I tried this, but I found that whilst it could speed up the resilver (and sc= rubs) by as much as 25% it also had a performance hit were reads (particular= ly streaming video - which is what my server mostly did) would =E2=80=9Cpaus= e=E2=80=9D and =E2=80=9Cstutter=E2=80=9D .. the balance came when I brought i= t back to around 200 * 15) . It would still stutter when running multiple streams (to the point of heavy l= oad) but that was kinda expected... I tried to keep the load distributed off= it and let the other front end servers stream and it seemed to result in a h= ealthy balance. >=20 > -Alan > _______________________________________________ > freebsd-stable@freebsd.org mailing list > https://lists.freebsd.org/mailman/listinfo/freebsd-stable > To unsubscribe, send any mail to "freebsd-stable-unsubscribe@freebsd.org"
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