From owner-freebsd-questions@FreeBSD.ORG Tue Mar 4 08:58:31 2014 Return-Path: <owner-freebsd-questions@FreeBSD.ORG> 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 ESMTPS id A6624AC5 for <freebsd-questions@freebsd.org>; Tue, 4 Mar 2014 08:58:31 +0000 (UTC) Received: from blue.qeng-ho.org (blue.qeng-ho.org [217.155.128.241]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mx1.freebsd.org (Postfix) with ESMTPS id 24B625F8 for <freebsd-questions@freebsd.org>; Tue, 4 Mar 2014 08:58:30 +0000 (UTC) Received: from fileserver.home.qeng-ho.org (localhost [127.0.0.1]) by fileserver.home.qeng-ho.org (8.14.7/8.14.5) with ESMTP id s248wMbV097765; Tue, 4 Mar 2014 08:58:22 GMT (envelope-from freebsd@qeng-ho.org) Message-ID: <531595AE.9060402@qeng-ho.org> Date: Tue, 04 Mar 2014 08:58:22 +0000 From: Arthur Chance <freebsd@qeng-ho.org> User-Agent: Mozilla/5.0 (X11; FreeBSD amd64; rv:24.0) Gecko/20100101 Thunderbird/24.3.0 MIME-Version: 1.0 To: Chris Stankevitz <chrisstankevitz@gmail.com>, freebsd-questions <freebsd-questions@freebsd.org> Subject: Re: ZFS, GPTIDs, and using the whole disk References: <CAPi0psuD5zDBuBZmE3tBKDeFdMcpvBn3pU4waDu6FU8SaTs0-Q@mail.gmail.com> In-Reply-To: <CAPi0psuD5zDBuBZmE3tBKDeFdMcpvBn3pU4waDu6FU8SaTs0-Q@mail.gmail.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-BeenThere: freebsd-questions@freebsd.org X-Mailman-Version: 2.1.17 Precedence: list List-Id: User questions <freebsd-questions.freebsd.org> List-Unsubscribe: <http://lists.freebsd.org/mailman/options/freebsd-questions>, <mailto:freebsd-questions-request@freebsd.org?subject=unsubscribe> List-Archive: <http://lists.freebsd.org/pipermail/freebsd-questions/> List-Post: <mailto:freebsd-questions@freebsd.org> List-Help: <mailto:freebsd-questions-request@freebsd.org?subject=help> List-Subscribe: <http://lists.freebsd.org/mailman/listinfo/freebsd-questions>, <mailto:freebsd-questions-request@freebsd.org?subject=subscribe> X-List-Received-Date: Tue, 04 Mar 2014 08:58:31 -0000 On 03/03/2014 23:47, Chris Stankevitz wrote: > Please identify any false statements: > > 1. ZFS prefers to use the entire disk. > > 2. The only way to refer to an entire disk is by the device name e.g. /dev/da4 > > 3. Device names like /dev/da4 are not persistently connected to actual > SATA ports on your motherboard/expander. For example, if you start > hot swapping disks, even if you put them back in the same slot, their > device names might change. Even if you don't hot swap, the device > name for a particular disk might change for other reasons (e.g. if you > have a USB drive plugged in during boot). It's possible to permanently fix drive number assignments to particular physical interfaces via /boot/device.hints - see the man page for details. For instance, because of the motherboard I use the default naming of my disks would have the system disk on ada3 and my not usually occupied eSATA devices would be ada[01], and I prefer my system disk to be disk 0 so my device.hints contains # bring sense to the disks now we're on ahci. # We also renumber the SCSI buses so the ICH9 controller # handles scbus0-5 and the JMicron controller handles # scbus[67]. # hint.scbus.0.at="ahcich2" hint.scbus.1.at="ahcich3" hint.scbus.2.at="ahcich4" hint.scbus.3.at="ahcich5" hint.scbus.4.at="ahcich6" hint.scbus.5.at="ahcich7" hint.scbus.6.at="ahcich0" hint.scbus.7.at="ahcich1" # # This makes the system disk ada0, the ZFS raidz # ada[123], the 2 eSATA ports ada[56] # hint.ada.0.at="scbus0" hint.ada.1.at="scbus1" hint.ada.2.at="scbus2" hint.ada.3.at="scbus3" hint.ada.4.at="scbus4" # The cd is on the last ICH9 port hint.cd.0.at="scbus5" # eSata devices hint.ada.5.at="scbus6" hint.ada.6.at="scbus7" > 4. Because of (3) it is dangerous to use device names when building a zpool > > 5. GPTIDs are persistently attached to physical drives. > > 5a. This is because the GPTID is written on the disk when you create the GPTID. > > 6. A GPTID does not refer to an entire disk. > > 6a. A GPTID refers to a partition > > 7. You can create a zpool of GPTIDs > > 8. A zpool created from GPTIDs will not be using the entire disk. > > 9. You cannot simultaneously allow ZFS access to the entire disk while > keeping persistent names/labels. > > Thank you,