From owner-freebsd-stable@FreeBSD.ORG Thu Nov 26 10:29:18 2009 Return-Path: Delivered-To: freebsd-stable@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34]) by hub.freebsd.org (Postfix) with ESMTP id A791A1065778 for ; Thu, 26 Nov 2009 10:29:18 +0000 (UTC) (envelope-from swhetzel@gmail.com) Received: from mail-iw0-f198.google.com (mail-iw0-f198.google.com [209.85.223.198]) by mx1.freebsd.org (Postfix) with ESMTP id 6F85F8FC12 for ; Thu, 26 Nov 2009 10:29:18 +0000 (UTC) Received: by iwn36 with SMTP id 36so359159iwn.3 for ; Thu, 26 Nov 2009 02:29:17 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=gamma; h=domainkey-signature:mime-version:received:in-reply-to:references :date:message-id:subject:from:to:cc:content-type; bh=MT0val/IshjR+hhTv1ONkj6Oe+NNH1l17TgvKcliQ54=; b=Exo6n78dxj7ry9Dm7aMfM2JKwsLpLHt/4+2YMdTbjI6TV5d+cb0zvv0ZA0haqKwMwE zVuZhMMFC9EmT1mGFeZ34pJLV5msRARgmrgtY7NP8ndQaz9eLlV/0XZtpCugmgDG+71/ O9j9xjRboiryfLrPuuZAknAcIXfEkZLjJ2bvs= DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=mime-version:in-reply-to:references:date:message-id:subject:from:to :cc:content-type; b=E/hiLE6kRK33Q0lTVW6vtZVHYKmmjrAIrJlQNAXZ7I8DqzavfyYItg+AnNlokrGCAa mEGlJWG8VFY7MZUD9dG+uLv8Lm8HUlvo6ot0B414oa04ss4LDVpf9Mar2eHPBzsOevy8 0tuiDwh1T71ruVLd7AarQU7Zn87ABDTi/QsTE= MIME-Version: 1.0 Received: by 10.231.120.136 with SMTP id d8mr2090610ibr.14.1259231357818; Thu, 26 Nov 2009 02:29:17 -0800 (PST) In-Reply-To: <20091126085034.GA51998@icarus.home.lan> References: <4B0E3ABA.3030606@tzim.net> <790a9fff0911260040i1456d7c0j4f8327d24d2966cf@mail.gmail.com> <20091126085034.GA51998@icarus.home.lan> Date: Thu, 26 Nov 2009 04:29:17 -0600 Message-ID: <790a9fff0911260229u40d9f499w28a7ce46e1f92467@mail.gmail.com> From: Scot Hetzel To: Jeremy Chadwick Content-Type: text/plain; charset=ISO-8859-1 Cc: freebsd-stable@freebsd.org Subject: Re: Can't use gpt labels re-importing pool X-BeenThere: freebsd-stable@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: Production branch of FreeBSD source code List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Thu, 26 Nov 2009 10:29:18 -0000 On 11/26/09, Jeremy Chadwick wrote: > I'm a bit curious about something, so maybe someone can help me > understand: > > Why are people bothering with GPT labels (or in some cases, glabels) > when AHCI (whether it be ataahci.ko or ahci.ko) is in use? Under what > circumstance would the device name change dynamically in this situation? > There was a thread about this problem where the drives had changed their device names due to a change in the kernel drive (Current list from July): http://lists.freebsd.org/pipermail/freebsd-current/2009-July/009377.html Through out this thread there were various suggests on how he could recover the system, and prevent the problem from occurring in the future. One of the suggestions was that use of zpool replace to change from device names to using glabel labels. http://lists.freebsd.org/pipermail/freebsd-current/2009-July/009440.html > I've never witnessed this happening with AHCI, at least on Intel > systems, and I've hot-swapped hard disks many times over. > Using glabels, gpt labels, or gptid solves the problem of not needing to remember which device name the drive originally had. For instance, on a zfs zraid pool with 3 disks (ad1 ad2 ad3) you could disconnect the pool from one computer and connect it to another system and it wouldn't matter which order you reconnected the drives (1 2 3 or 3 1 2) as the pool would still be recognized when it is imported on the new system. Also if the new system already has drives ad1 and ad2, it wouldn't matter. Scot