From owner-freebsd-questions@FreeBSD.ORG Sun Sep 22 14:25:31 2013 Return-Path: Delivered-To: freebsd-questions@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:1900:2254:206a::19:1]) (using TLSv1 with cipher ADH-AES256-SHA (256/256 bits)) (No client certificate requested) by hub.freebsd.org (Postfix) with ESMTP id C2FC07DB for ; Sun, 22 Sep 2013 14:25:31 +0000 (UTC) (envelope-from wblock@wonkity.com) Received: from wonkity.com (wonkity.com [67.158.26.137]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.freebsd.org (Postfix) with ESMTPS id 5B99B249F for ; Sun, 22 Sep 2013 14:25:31 +0000 (UTC) Received: from wonkity.com (localhost [127.0.0.1]) by wonkity.com (8.14.7/8.14.7) with ESMTP id r8MEPOYE027487; Sun, 22 Sep 2013 08:25:24 -0600 (MDT) (envelope-from wblock@wonkity.com) Received: from localhost (wblock@localhost) by wonkity.com (8.14.7/8.14.7/Submit) with ESMTP id r8MEPOHU027484; Sun, 22 Sep 2013 08:25:24 -0600 (MDT) (envelope-from wblock@wonkity.com) Date: Sun, 22 Sep 2013 08:25:24 -0600 (MDT) From: Warren Block To: atar Subject: Re: dangerously dedicated physical disks. In-Reply-To: Message-ID: References: User-Agent: Alpine 2.00 (BSF 1167 2008-08-23) MIME-Version: 1.0 Content-Type: TEXT/PLAIN; format=flowed; charset=US-ASCII X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.4.3 (wonkity.com [127.0.0.1]); Sun, 22 Sep 2013 08:25:24 -0600 (MDT) Cc: "freebsd-questions@freebsd.org" 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: Sun, 22 Sep 2013 14:25:31 -0000 On Sun, 22 Sep 2013, atar wrote: > During the reading of the FreeBSD handbook, I've encountered at the term > 'dangerously dedicated' regarding physical disks and the author of this > chapter in the FreeBSD handbook didn't think this term need more clarity. so > for newbies like me in the FreeBSD world I want to ask: what's the > 'dangerously dedicated' term meaning by? The term refers to a disk partitioned with only the BSD disklabel partition table: disk ada0 partition "a" (ada0a, /) partition "b" (ada0b, swap) partition "d" (ada0d, /var) partition "e" (ada0e, /tmp) partition "f" (ada0f, /usr) It's "dangerous" because that partitioning format is rare outside of BSD-based systems. Disk utilities may not recognize it, and could damage it. Most of the rest of the world used MBR partitioning, which allowed up to four MBR partitions (called "slices" by FreeBSD) per disk. Since four slices is not enough for the standard FreeBSD disk layout, with /, swap, /var, /tmp, and /usr, the standard procedure is to use MBR partitioning, with the MBR partitions ("slices") being sub-partitioned by a BSD disklabel. disk ada0 MBR slice 1 (ada0s1) partition "a" (ada0s1a, /) partition "b" (ada0s1b, swap) partition "d" (ada0s1d, /var) partition "e" (ada0s1e, /tmp) partition "f" (ada0s1f, /usr) MBR slice 2 (ada0s2) ... Yes, one partition format inside another. It only seems complicated because it is. GPT is the new partitioning format, which makes things much simpler by being capable of up to 128 partitions in the standard configuration. With GPT, there is no reason to use BSD disklabels at all. disk ada0 GPT partition 1 (ada0p1, bootcode) GPT partition 2 (ada0p2, /) GPT partition 3 (ada0p3, swap) GPT partition 4 (ada0p4, /var) GPT partition 5 (ada0p5, /tmp) GPT partition 6 (ada0p6, /usr) Summary: "Dangerously dedicated" partitioning has no unique advantages. Use GPT when possible, use MBR/disklabel when necessary.