From owner-freebsd-geom@FreeBSD.ORG Mon Mar 8 18:41:02 2010 Return-Path: Delivered-To: freebsd-geom@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34]) by hub.freebsd.org (Postfix) with ESMTP id C85CA106566C for ; Mon, 8 Mar 2010 18:41:02 +0000 (UTC) (envelope-from swhetzel@gmail.com) Received: from mail-iw0-f199.google.com (mail-iw0-f199.google.com [209.85.223.199]) by mx1.freebsd.org (Postfix) with ESMTP id 90B118FC17 for ; Mon, 8 Mar 2010 18:41:02 +0000 (UTC) Received: by iwn37 with SMTP id 37so386426iwn.27 for ; Mon, 08 Mar 2010 10:41:02 -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=AFt5isUbk6o7ziADcQ/Ohv1EUlTLxuVrTlbqx0Izqrc=; b=o34sdK0uwUU8WmSp8ZOYTUWu7rrLERoqKtvJ1CGDAZ16dLCRKTqPoLfBSo/NXNTvsH t+cG8d2XUnALXPWPV6R09i6B1fn3XBzwEwJ7Wh4G28pl5P5H5fyX5b0PZTEpnAVF6Kj1 mqbSYyCyPFsvJe78j77KMAXroN7HieIeNMZ88= 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=djWoq3bIahaJUV2gsezVPyMb70w/rDPMFoxG4WHCyAHhXr9dHVW8ohrfG0EBh7P8Fo XfPzjrc07LJaMy6FZLkJLiYtE4gcTq1IxVWx4lskaOsDXKSCwxq8VMfYRfyeRIuFk7Ck u8aN6aDWnCOsYDLDlHv41Zf13GA+vlDd2ABcU= MIME-Version: 1.0 Received: by 10.231.148.18 with SMTP id n18mr143867ibv.7.1268072210567; Mon, 08 Mar 2010 10:16:50 -0800 (PST) In-Reply-To: References: <761C8533-B1DC-4DC7-8B2E-9CB1A8A5BEF8@mac.com> Date: Mon, 8 Mar 2010 12:16:50 -0600 Message-ID: <790a9fff1003081016q2b6a7d93qa55055aaaa9cf74@mail.gmail.com> From: Scot Hetzel To: Pete French Content-Type: text/plain; charset=ISO-8859-1 Cc: xcllnt@mac.com, avg@icyb.net.ua, freebsd-geom@freebsd.org Subject: Re: another gpt vs mbr (sanity) check 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: Mon, 08 Mar 2010 18:41:02 -0000 On Mon, Mar 8, 2010 at 11:48 AM, Pete French wrote: >> To clarify: the protective MBR is there only to protect the GPT >> disk from tools that do not understand the GPT. Any GPT-aware >> tool will treat the disk as a GPT disk. Consequently: the MBR >> is inferior to the GPT... > > The queston is then, why isn't Windows treating it as GPT ? It's I have both MBR and GPT formated drives installed in my laptop, and Windows 7 correctly identifies both drives. The GPT drive was formated using FreeBSD 8. > all very nice in theory, but if the practical upshot is that > we get flash media which will read perfectly well in all operating > systems except for BSD then thats not a good result, even if it > is theoretically correct. Which is the situation the original poster > appeared to have. > The problem the original poster was having is this: Format drive as GPT Re-Format drive as MBR FreeBSD still sees the drive as GPT instead of MBR. The reason is that FreeBSD is still detecting the Seconday GPT which is located at the end of the disk, and using it due to the Primary GPT was lost/corrupted when the drive was reformated as MBR disk. The real question is how was the drive reformated. If it was reformated using gpart: - Delete all existing partitions: gpart delete -i X adY - Destroy the GPT formated drive gpart destroy adY - Create the MBR formated drive gpart create -s mbr adY And the secondary GPT header still exists, then it is a FreeBSD bug. But if it was reformated using a different tool, then it is a bug in that tool for not reconizing that the original disk was formated as GPT. Scot