Date: Mon, 25 Apr 2011 21:24:09 +0100 From: krad <kraduk@gmail.com> To: Sergio de Almeida Lenzi <lenzi.sergio@gmail.com> Cc: freebsd-questions@freebsd.org Subject: Re: ZFS performance strangeness Message-ID: <BANLkTimyRPjRe2ntv07MXjBW0%2BwqOmr_zw@mail.gmail.com> In-Reply-To: <1303662094.42253.4.camel@z6000.lenzicasa> References: <espd78-2at.ln1@it-betrieb.de> <1303662094.42253.4.camel@z6000.lenzicasa>
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On 24 April 2011 17:21, Sergio de Almeida Lenzi <lenzi.sergio@gmail.com>wro= te: > Em Ter, 2011-04-12 =E0s 13:33 +0200, Lars Wilke escreveu: > > > Hi, > > > > There are quite a few threads about ZFS and performance difficulties, > > but i did not find anything that really helped :) > > Therefor any advice would be highly appreciated. > > I started to use ZFS with 8.1R, only tuning i did was setting > > > > vm.kmem_size_scale=3D"1" > > vfs.zfs.arc_max=3D"40000M" > > For me I solved the ZFS performace in FreeBSD and postgres databases > (about 100GB size) > by tunning vm.kmem_size to atout 3/4 of the ram size... > in your case, vm.kmem_size=3D(48 *3/4)=3D36G, it puts almost all the > database > in memory and it is now lightning fast... > I use to disable prefetch in zfs.. too > > Hope this can help, > > Sergio > _______________________________________________ > freebsd-questions@freebsd.org mailing list > http://lists.freebsd.org/mailman/listinfo/freebsd-questions > To unsubscribe, send any mail to " > freebsd-questions-unsubscribe@freebsd.org" > wouldnt it be better to allow the db to use the memory rather than zfs, as this would involve far less context switches?
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