From owner-freebsd-fs@FreeBSD.ORG Wed Jan 14 16:38:11 2015 Return-Path: Delivered-To: freebsd-fs@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [8.8.178.115]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by hub.freebsd.org (Postfix) with ESMTPS id 19AE9F5A for ; Wed, 14 Jan 2015 16:38:11 +0000 (UTC) Received: from kirk-ext.obspm.fr (kirk-ext.obspm.fr [145.238.193.7]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (Client CN "*.obspm.fr", Issuer "TERENA SSL CA" (verified OK)) by mx1.freebsd.org (Postfix) with ESMTPS id ADC579EA for ; Wed, 14 Jan 2015 16:38:10 +0000 (UTC) Received: from pcjas.obspm.fr (pcjas.obspm.fr [145.238.184.233]) (authenticated bits=0) by kirk-ext.obspm.fr (8.14.4/8.14.4/DIO Observatoire de Paris - 15/04/10) with ESMTP id t0EGc6O6021020 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Wed, 14 Jan 2015 17:38:07 +0100 Date: Wed, 14 Jan 2015 17:38:49 +0100 From: Albert Shih To: Linda Kateley Subject: Re: How many ram... Message-ID: <20150114163849.GA97640@pcjas.obspm.fr> References: <20150113105240.GA33162@pcjas.obspm.fr> <54B528AC.9090901@kateley.com> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <54B528AC.9090901@kateley.com> User-Agent: Mutt/1.5.23 (2014-03-12) X-Greylist: Sender succeeded SMTP AUTH, not delayed by milter-greylist-4.3.9 (kirk-ext.obspm.fr [145.238.193.20]); Wed, 14 Jan 2015 17:38:07 +0100 (CET) X-Virus-Scanned: clamav-milter 0.98.5 at kirk-ext.obspm.fr X-Virus-Status: Clean Cc: freebsd-fs@freebsd.org X-BeenThere: freebsd-fs@freebsd.org X-Mailman-Version: 2.1.18-1 Precedence: list List-Id: Filesystems List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Wed, 14 Jan 2015 16:38:11 -0000 Le 13/01/2015 à 08:16:12-0600, Linda Kateley a écrit > Jas, > > Most of those rules of thumbs are not valid. ZFS doesn't really need to > keep data about metadata in ram. It keeps recently used and frequently > used items in cache. There are some per disk caches but by default those > are pretty small. > > I have a blog on a group that has a 350TB archive/backup system with > 32GB ram. http://kateleyco.com/?p=815 That's very conforting ;-) That's mean I didn't need to by 1To of Ram when I go to 1Po file server. > > Everything is dependent on use case. If you have many users all using > the same file, frequently.. that will be cached. Sizing workload helps. Thanks you to everyone. Regards. JAS -- Albert SHIH DIO bâtiment 15 Observatoire de Paris 5 Place Jules Janssen 92195 Meudon Cedex France Téléphone : +33 1 45 07 76 26/+33 6 86 69 95 71 xmpp: jas@obspm.fr Heure local/Local time: mer 14 jan 2015 17:35:13 CET