From owner-freebsd-fs@FreeBSD.ORG Wed Jan 14 16:57:45 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 EEC936F8 for ; Wed, 14 Jan 2015 16:57:45 +0000 (UTC) Received: from mail-ie0-f169.google.com (mail-ie0-f169.google.com [209.85.223.169]) (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 B68F4BFA for ; Wed, 14 Jan 2015 16:57:45 +0000 (UTC) Received: by mail-ie0-f169.google.com with SMTP id y20so9939546ier.0 for ; Wed, 14 Jan 2015 08:57:39 -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:reply-to:organization :user-agent:mime-version:to:cc:subject:references:in-reply-to :content-type:content-transfer-encoding; bh=ibOmvctrWyC4lqCw00mgj9lCmfVmYBu2RM4q2J8xGdI=; b=dM86D0IXKHZuVxTclpayvHWcPpF/2EUKDxjCLu3HXsZitIyVBIGii90asx5W4Pwr26 +XY1OIzVysVb1qoITzV7YAsDUTI63wrCPiglmzL55uh43hE0QqQXLV2BcpjTf2UNFGMJ L+NprDhgZ5baTOaUuzCvNBB4I4jE59BLXVmvh2Dd0p0fPW3p/I8aOsQqj72Ex+0DoEN5 nxhJyOYGSXY6MdbK1K2xc4t3OVFHWjxnSDsl5ie6mvXig8c7SmA3CLvHOC97+j1g4O0k St95y2b2Uu2Obp3G4PR7hNiuqlmWVfnb6kZbqYYrUSFqDjeecLoPKDluon6buhXHTfjZ kpVA== X-Gm-Message-State: ALoCoQmiuy9o1wZecdwKVNpSYv+I7G2BIoqaEyFBWhrM52oI3MwERFuE8XHYJuE+Ayu1YHvadz9P X-Received: by 10.50.79.167 with SMTP id k7mr5390524igx.26.1421254220445; Wed, 14 Jan 2015 08:50:20 -0800 (PST) Received: from [192.168.0.18] ([63.231.252.189]) by mx.google.com with ESMTPSA id g20sm8166574igt.14.2015.01.14.08.50.19 (version=TLSv1.2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Wed, 14 Jan 2015 08:50:19 -0800 (PST) Message-ID: <54B69E4A.9010402@kateley.com> Date: Wed, 14 Jan 2015 10:50:18 -0600 From: Linda Kateley Reply-To: linda@kateley.com Organization: Kateley Company 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: Albert Shih Subject: Re: How many ram... References: <20150113105240.GA33162@pcjas.obspm.fr> <54B528AC.9090901@kateley.com> <20150114163849.GA97640@pcjas.obspm.fr> In-Reply-To: <20150114163849.GA97640@pcjas.obspm.fr> Content-Type: text/plain; charset=windows-1252; format=flowed Content-Transfer-Encoding: 8bit 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 16:57:46 -0000 I will say one more thing.. I also have a customer who uses zfs for security camera storage. The cameras deliver 100's of k bytes per minute... But they save the data for a very very very long time. That kind of system would need very little ram(maybe 8GB) but lots and lots of disk. lk On 1/14/15 10:38 AM, Albert Shih wrote: > 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