From owner-freebsd-questions@FreeBSD.ORG Mon Jul 9 10:16:11 2012 Return-Path: Delivered-To: freebsd-questions@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [69.147.83.52]) by hub.freebsd.org (Postfix) with ESMTP id 8AF69106564A for ; Mon, 9 Jul 2012 10:16:11 +0000 (UTC) (envelope-from freebsd@edvax.de) Received: from mx02.qsc.de (mx02.qsc.de [213.148.130.14]) by mx1.freebsd.org (Postfix) with ESMTP id 3265B8FC12 for ; Mon, 9 Jul 2012 10:16:11 +0000 (UTC) Received: from r56.edvax.de (port-92-195-60-31.dynamic.qsc.de [92.195.60.31]) by mx02.qsc.de (Postfix) with ESMTP id 5F0C128068; Mon, 9 Jul 2012 12:16:09 +0200 (CEST) Received: from r56.edvax.de (localhost [127.0.0.1]) by r56.edvax.de (8.14.5/8.14.5) with SMTP id q69AG8fU001920; Mon, 9 Jul 2012 12:16:08 +0200 (CEST) (envelope-from freebsd@edvax.de) Date: Mon, 9 Jul 2012 12:16:08 +0200 From: Polytropon To: "Thomas Mueller" Message-Id: <20120709121608.1bce238e.freebsd@edvax.de> In-Reply-To: <47.B3.06836.B9F4AFF4@smtp02.insight.synacor.com> References: <47.B3.06836.B9F4AFF4@smtp02.insight.synacor.com> Organization: EDVAX X-Mailer: Sylpheed 3.1.1 (GTK+ 2.24.5; i386-portbld-freebsd8.2) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Cc: Carmel , Polytropon , freebsd-questions@freebsd.org Subject: Re: Format a USB flash drive using gpart X-BeenThere: freebsd-questions@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list Reply-To: Polytropon List-Id: User questions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Mon, 09 Jul 2012 10:16:11 -0000 On Sun, 08 Jul 2012 23:27:23 -0400, Thomas Mueller wrote: > You mean the non-subdivided 1.44 MB or other capacity of a floppy > is called a partition? Let's try to use the correct terminology. If you're talking about an MS-DOS disk, then yes, it contains a DOS partition which is formatted. In FreeBSD, we would call it a slice (slice == "DOS primary partition"). In this case, there is no (sub)partitioning, the _slice_ carries the MS-DOS file system here. You know that MS-DOS does not have support for partitioning. > Same question for CDs? Not sure. A CD contains an ISO-9660 file system without an enclosing partition per se. If we look back into OS history, we find the magical 'c' partition. Historically, partition letters have been reserved for specific purposes: the 'a' partition means a bootable partition, 'b' is a swap partition, and 'c' is "the whole disk", refering either to the disk device (da0c == da0) or the whole slice (da0s1c == da0s1). You _can_ put a UFS file system, even many of them, on a CD, that is possible, but don't expect any "Windows" to be able to deal with it. :-) > Also, a file system can be contained in an image file. Or is this > a virtual partition? As devices and "real files" are "quite the same", you can mount a file system that is contained in a file. You typically do this when doing data recovery and forensic analysis, where your starting point is an image file of a disk, a slice or a partition. You then "connect" it to a virtual node (vnconfig - e. g. md0) and then you mount it as if it was a device file. > Might > # tar xf /dev/da0 > work in other BSDs or even other (quasi-)Unixes including Linux, > using the appropriate device name where applicable in place of da0? That's quite possible. I've been speaking about tar as "the most universal file system which isn't one" -- I've been using it on floppies many many years ago, to transfer data among Sun Sparcstations, Linux workstations and a BSD server. It's important not to use any "fancy" tar features, and of course you need to know the device names corresponding to the floppy drive which differ across the systems, but it is possible to first use fdformat, then tar cf, then tar xf. This of course happened before the dawn of networking. :-) > While that particular construst could probably not be booted, > it is possible to boot from a floppy or image file that does > not contain a file system. For bare booting, a file system isn't that essential. You just have to make sure the "boot chain" is properly resolved, such as for example the FreeBSD boot mechanism works. You can read more about it in "man 8 boot". > Some of the disk images on the System Rescue CD (sysresccd.org) > are not viewable/mountable as file systems. I haven't looked into this particular one, but that is very well possible. A CD doesn't _need_ to be in a ISO-9660 format (even though it's the default data format). The _implementation_ of the boot mechanism matters: it could even select from several different boot images stored in some arbitrary (but addressable) manner on the CD. -- Polytropon Magdeburg, Germany Happy FreeBSD user since 4.0 Andra moi ennepe, Mousa, ...