From owner-freebsd-geom@FreeBSD.ORG Sat Sep 17 04:17:07 2005 Return-Path: X-Original-To: freebsd-geom@freebsd.org Delivered-To: freebsd-geom@freebsd.org Received: from mx1.FreeBSD.org (mx1.freebsd.org [216.136.204.125]) by hub.freebsd.org (Postfix) with ESMTP id 1315916A41F for ; Sat, 17 Sep 2005 04:17:07 +0000 (GMT) (envelope-from sudakov@sibptus.tomsk.ru) Received: from relay2.tomsk.ru (relay2.tomsk.ru [212.73.124.8]) by mx1.FreeBSD.org (Postfix) with ESMTP id 2C9B543D45 for ; Sat, 17 Sep 2005 04:17:04 +0000 (GMT) (envelope-from sudakov@sibptus.tomsk.ru) X-Virus-Scanned: by Dr.Web (R) daemon for FreeBSD, version 4.32.1 (2004-08-30) at relay2.tomsk.ru X-Spam-Checker-Version: SpamAssassin 3.0.4 on relay2.tomsk.ru Received: from [172.16.138.125] (account sudakovva@sibptus.tomsk.ru HELO admin.sibptus.tomsk.ru) by relay2.tomsk.ru (CommuniGate Pro SMTP 4.3.2) with ESMTPSA id 1206478; Sat, 17 Sep 2005 11:17:01 +0700 Received: (from sudakov@localhost) by admin.sibptus.tomsk.ru (8.12.9p2/8.12.9/Submit) id j8H4H0Gk046875; Sat, 17 Sep 2005 11:17:00 +0700 (OMSST) (envelope-from sudakov) Date: Sat, 17 Sep 2005 11:17:00 +0700 From: Victor Sudakov To: Danny Howard Message-ID: <20050917041700.GA46650@admin.sibptus.tomsk.ru> References: <20050916073012.GA31056@admin.sibptus.tomsk.ru> <20050916225527.GT11689@ratchet.nebcorp.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20050916225527.GT11689@ratchet.nebcorp.com> User-Agent: Mutt/1.4.2.1i Organization: AO "Svyaztransneft", SibPTUS X-PGP-Key: http://vas.tomsk.ru/vas.asc Cc: freebsd-geom@freebsd.org Subject: Re: Create a mirror on disk with valid data X-BeenThere: freebsd-geom@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: GEOM-specific discussions and implementations List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Sat, 17 Sep 2005 04:17:07 -0000 Danny Howard wrote: > > I have only ever mirrored disks with data on them. Its a question of > bootstrap - does the mirror comes first or does the data you are going > to mirror come first? Suppose the disk has valuable data in the last sector and you are going to create a mirror from this disk. What is going to happen when the last sector is overwritten with the mirror metadata? Your data will be lost, right? Suppose you need to access the last sector, access will be denied, right? > > My crib sheet is at > http://dannyman.toldme.com/2005/01/24/freebsd-howto-gmirror-system/ I have read this document. Have you ever tried to newfs a partition you have mirrored this way? Look at my second mail (screen output), it seems that such a partition cannot be newfs'ed without changing the label, because access to the last sector is denied. Please try to: 1. fdisk and label a disk, create a partition that occupies the whole disk. "disklabel -w ad0s1 auto" will automatically create an "a" partition for you. 2. create a mirror from this disk, e.g. "gmirror label gm1 ad0" 3. newfs /dev/mirror/gm1s1a and see what happens. -- Victor Sudakov, VAS4-RIPE, VAS47-RIPN