From owner-freebsd-questions@FreeBSD.ORG Sat Aug 20 19:23:23 2011 Return-Path: Delivered-To: freebsd-questions@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34]) by hub.freebsd.org (Postfix) with ESMTP id 03266106564A for ; Sat, 20 Aug 2011 19:23:23 +0000 (UTC) (envelope-from amvandemore@gmail.com) Received: from mail-fx0-f54.google.com (mail-fx0-f54.google.com [209.85.161.54]) by mx1.freebsd.org (Postfix) with ESMTP id 903D38FC0C for ; Sat, 20 Aug 2011 19:23:22 +0000 (UTC) Received: by fxe4 with SMTP id 4so3435427fxe.13 for ; Sat, 20 Aug 2011 12:23:21 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=gamma; h=mime-version:in-reply-to:references:date:message-id:subject:from:to :cc:content-type; bh=9Sz8DoBSQvUm/odSJd+uM04Vywi5k/5R4f8vFXqITmk=; b=uiDmS6Dw07Xo8rg6Rkx5wxHGMrnee9FimGhZPJEt4OZ/6CmrlrAIKGNu8qiU7kFXpp 5UFGE+fUYK3hl7MmT7v9XVgXxpUJvu2gwhHsvqiIpFYUBQ51zNZxWSnDBqYZNMfzUrio I9rlfdrG1mAvPRIq1KPMd3NJ1Hli0y1GUdbEA= MIME-Version: 1.0 Received: by 10.223.6.91 with SMTP id 27mr1076562fay.145.1313868201381; Sat, 20 Aug 2011 12:23:21 -0700 (PDT) Received: by 10.223.120.72 with HTTP; Sat, 20 Aug 2011 12:23:21 -0700 (PDT) In-Reply-To: <4E4FFF23.406@rawbw.com> References: <4E4FFF23.406@rawbw.com> Date: Sat, 20 Aug 2011 14:23:21 -0500 Message-ID: From: Adam Vande More To: Yuri Content-Type: text/plain; charset=ISO-8859-1 X-Content-Filtered-By: Mailman/MimeDel 2.1.5 Cc: FreeBSD Questions Subject: Re: How much memory does ZFS use? X-BeenThere: freebsd-questions@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: User questions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Sat, 20 Aug 2011 19:23:23 -0000 On Sat, Aug 20, 2011 at 1:38 PM, Yuri wrote: > Someone told me that ZFS is a memory hog and it should be avoided as such. > Is this true? > A rather ridiculous statement you were told and full of ignorance in my opinion. The 1908 Ford Model T got 25 MPG and my 2006 Mazda Speed6 gets about 21 on the highway. Which one would you rather drive around and entrust with your family's safety? Look at it this way, computer performance has increased very rapidly(particularly in terms of CPU) over the last 30 years with one key exception: disk performance. ZFS, among it's other benefits, does what it can to mask this deficiency by offloading what it to more CPU and memory intensive operations. Offloading(where possible) slow disk to faster CPU and memory resources which many server and desktops already have in abundant excess is an excellent tradeoff IMO. What difference does it make if it's a kernel module or not in terms of memory usage? Either way, set the appropriate tunable to control memory usage and you're done. vfs.zfs.arc_max="2048M" -- Adam Vande More