From owner-freebsd-questions@FreeBSD.ORG Mon Jan 28 16:22:41 2013 Return-Path: Delivered-To: freebsd-questions@freebsd.org Received: from mx1.freebsd.org (mx1.FreeBSD.org [8.8.178.115]) by hub.freebsd.org (Postfix) with ESMTP id 1006AF3F for ; Mon, 28 Jan 2013 16:22:41 +0000 (UTC) (envelope-from paul@kraus-haus.org) Received: from mail-ve0-f177.google.com (mail-ve0-f177.google.com [209.85.128.177]) by mx1.freebsd.org (Postfix) with ESMTP id B043D979 for ; Mon, 28 Jan 2013 16:22:40 +0000 (UTC) Received: by mail-ve0-f177.google.com with SMTP id m1so1445491ves.36 for ; Mon, 28 Jan 2013 08:22:34 -0800 (PST) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20120113; h=x-received:subject:mime-version:content-type:from:in-reply-to:date :content-transfer-encoding:message-id:references:to:x-mailer :x-gm-message-state; bh=XLGo5YtjZkdT1/Beumdq2013BOX6Zrj4RqKur3AdXwI=; b=aMTQ5paTL7JOwRZOrNvlbKw2J9i6mc5NCGJBluvcfj+kqOCnbWu67YClZIhEL4ftig 7rv7Q+Ma1yWnh/lw47cchqlN+HVx32UZ+TqjXdppr3yJiLc9oI/DV/ZbD8CKnXprEWtH nSkCn9yl/pIqf/ZJ0/EyyNTNXAPReGHXaS7KxCUn6l0zH2I87oy3StidKGRVHbIyTIIe 93scLiyduBRuSdUu2rkOMReR84fpUooBtTnWn0D+JWTBxy6U8H2KtoC+RwDhEcaXMqUy dYzWPO5ZEK6mHlUhYap0TWqybTniMiUnpIfixgrnW2/7U0B0PRqRSOcKpNgE3BLWWgH7 H+Ag== X-Received: by 10.220.39.69 with SMTP id f5mr15522357vce.45.1359390154043; Mon, 28 Jan 2013 08:22:34 -0800 (PST) Received: from mini1.kraus-haus.org ([96.236.21.119]) by mx.google.com with ESMTPS id g5sm6480193vez.6.2013.01.28.08.22.32 (version=TLSv1 cipher=ECDHE-RSA-RC4-SHA bits=128/128); Mon, 28 Jan 2013 08:22:33 -0800 (PST) Subject: Re: Starting with ZFS on fresh install Mime-Version: 1.0 (Apple Message framework v1085) Content-Type: text/plain; charset=us-ascii From: Paul Kraus In-Reply-To: <201301281539.58864.jmc-freebsd2@milibyte.co.uk> Date: Mon, 28 Jan 2013 11:22:30 -0500 Content-Transfer-Encoding: quoted-printable Message-Id: <4982641D-5691-4CF3-8385-6A836E4AC2A3@kraus-haus.org> References: <201301281539.58864.jmc-freebsd2@milibyte.co.uk> To: FreeBSD Mailing List X-Mailer: Apple Mail (2.1085) X-Gm-Message-State: ALoCoQnJ/9p3JCLCyS+lQ61jv1Xd9XQNXSy3p6gyjaXgKIyl6RhTDmu4Ba+r9ehOQm1fkGOBSxsX X-BeenThere: freebsd-questions@freebsd.org X-Mailman-Version: 2.1.14 Precedence: list List-Id: User questions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Mon, 28 Jan 2013 16:22:41 -0000 On Jan 28, 2013, at 10:39 AM, Mike Clarke wrote: > If you're going to be using ZFS then you'll probably be better off not = having=20 > separate partitions and letting ZFS manage space allocation if you = want to=20 > limit the size of /var or any other part of the system, You can manage space within a ZFS pool, regardless of whether you give = the zpool whole disks or a partition. rootpool 6.13G 56.4G 31K none rootpool/do-not-remove 31K 1024M 31K none rootpool/root 5.01G 56.4G 5.01G / rootpool/tmp 60.5K 56.4G 60.5K /tmp rootpool/var 111M 56.4G 111M /var Shows a system with a rootpool and within the rootpool three separate = fielsyetms: / (root) /var /tmp You can control space usage with the zfs quota property. Note the rootpool/do-not-remove daatset. This has a quota and = reservation of 1 GB. It's purpose is to permit recovery in case the = zpool is accidentally filled. ZFS requires *some* free space top process = file / directory remove operations. If the zpool is completely filled = you will NOT be able to remove anything to free up space. By having a = dataset with a quota and reservation of 1 GB, that space is already = marked as used so it will not be allocated. If the remainder of the = zpool fills, then you can quiet the system (so running processes don't = steal the space you are about to free up), change the quota / = reservation (I like going down to 512 MB), and then remove some files / = directories to free up space.=20 Note that the zpool itself (rootpool) is NOT used as a dataset and is = NOT mounted. My experience with ZFS under Solaris taught me that while = you *can* use that dataset, if you have any child datasets (and any = other datasets created will, by definition, be children of the rootpool) = you will end up with hierarchical datasets. This means that future = operations on datasets will have to take place in very specific order = (such as mounting and un mounting). By avoiding hierarchical datasets = (that are actually used) you avoid that complexity. -- Paul Kraus Deputy Technical Director, LoneStarCon 3 Sound Coordinator, Schenectady Light Opera Company