From owner-freebsd-fs@FreeBSD.ORG Tue Jan 13 14:23:49 2015 Return-Path: Delivered-To: freebsd-fs@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:1900:2254:206a::19:1]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by hub.freebsd.org (Postfix) with ESMTPS id 0CE6A3CE for ; Tue, 13 Jan 2015 14:23:49 +0000 (UTC) Received: from mail-ig0-f170.google.com (mail-ig0-f170.google.com [209.85.213.170]) (using TLSv1 with cipher ECDHE-RSA-RC4-SHA (128/128 bits)) (Client CN "smtp.gmail.com", Issuer "Google Internet Authority G2" (verified OK)) by mx1.freebsd.org (Postfix) with ESMTPS id CC99474B for ; Tue, 13 Jan 2015 14:23:48 +0000 (UTC) Received: by mail-ig0-f170.google.com with SMTP id l13so3742605iga.1 for ; Tue, 13 Jan 2015 06:23:41 -0800 (PST) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20130820; h=x-gm-message-state:message-id:date:from:user-agent:mime-version:to :subject:references:in-reply-to:content-type :content-transfer-encoding; bh=5dn/Do5moZOQ4924YfXNFnli6C9lnke6tSzxYQA0sO8=; b=kWXDT7seLg5bz5bSysHhdu2EwhuZ5P8DNnJwrTFdMK2O2DhUSV8wfSVBJ7noRITVFV 9Vw8hehlPwXMq9OsrQQdjwsvHm4z/4k0b+f/cufux9fAoB9Hvki/uKY6zLAxWLLmSb1q oGkMOPrJMkpeu789D1bGRJj9VJI5c3oxlsNBYtsGDhXMiodbL+rFnRQWIZiFJKT89BaW LUZbuOKUX2T0gq269dQjnerH3/tqpy7a56j4A8Pilun3n9hzgmE5cO9V9mgMxdSYKoGy R4z2nOICMdAuARRySEcq5tYmksqZJ4TesdCFSyXD8f/W9XHqCppO0skC6jZeTPt97/9B nA3A== X-Gm-Message-State: ALoCoQnGq5ya2NWw0PTVI4LnG27VudqGu6DytC2dGKWgFeWxDR2KHaWDSwST4zx4xRvzS25gcQbZ X-Received: by 10.42.151.67 with SMTP id d3mr28819440icw.56.1421158573600; Tue, 13 Jan 2015 06:16:13 -0800 (PST) Received: from kateleycoimac.local ([63.231.252.189]) by mx.google.com with ESMTPSA id qn2sm6143985igb.10.2015.01.13.06.16.12 for (version=TLSv1.2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Tue, 13 Jan 2015 06:16:12 -0800 (PST) Message-ID: <54B528AC.9090901@kateley.com> Date: Tue, 13 Jan 2015 08:16:12 -0600 From: Linda Kateley User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.10; rv:31.0) Gecko/20100101 Thunderbird/31.3.0 MIME-Version: 1.0 To: freebsd-fs@freebsd.org Subject: Re: How many ram... References: <20150113105240.GA33162@pcjas.obspm.fr> In-Reply-To: <20150113105240.GA33162@pcjas.obspm.fr> Content-Type: text/plain; charset=windows-1252; format=flowed Content-Transfer-Encoding: 8bit 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: Tue, 13 Jan 2015 14:23:49 -0000 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 Everything is dependent on use case. If you have many users all using the same file, frequently.. that will be cached. Sizing workload helps. linda On 1/13/15 4:52 AM, Albert Shih wrote: > Hi all, > > Basic question : How many amount of ram I need for running ZFS with a pool > of ~500-600To. > > For example If I've a server with 2 disk array of 60 disk of 6To. > > Is the rule I find somewhere on Internet saying for ZFS 1To --> 1Go is > still true ? > > What's happen If I use less ram ? Like 1To --> 0.5Go ? Less performance ? crash ? > > 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: > mar 13 jan 2015 11:49:16 CET > _______________________________________________ > freebsd-fs@freebsd.org mailing list > http://lists.freebsd.org/mailman/listinfo/freebsd-fs > To unsubscribe, send any mail to "freebsd-fs-unsubscribe@freebsd.org" -- Linda Kateley Kateley Company Skype ID-kateleyco http://kateleyco.com