From owner-freebsd-questions@FreeBSD.ORG Sun May 3 10:31:16 2015 Return-Path: Delivered-To: freebsd-questions@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:1900:2254:206a::19:1]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by hub.freebsd.org (Postfix) with ESMTPS id 94E6F906 for ; Sun, 3 May 2015 10:31:16 +0000 (UTC) Received: from outbound-queue-1.mail.thdo.gradwell.net (outbound-queue-1.mail.thdo.gradwell.net [212.11.70.34]) by mx1.freebsd.org (Postfix) with ESMTP id 2807E1DE0 for ; Sun, 3 May 2015 10:31:15 +0000 (UTC) Received: from outbound-edge-2.mail.thdo.gradwell.net (bonnie.gradwell.net [212.11.70.2]) by outbound-queue-1.mail.thdo.gradwell.net (Postfix) with ESMTP id AD27921F93 for ; Sun, 3 May 2015 11:30:07 +0100 (BST) Received: from cpc7-jarr12-2-0-cust882.16-2.cable.virginm.net (HELO amd.asgard.uk) (92.238.71.115) (smtp-auth username fbsd%pop3.dgmm.net, mechanism plain) by outbound-edge-2.mail.thdo.gradwell.net (qpsmtpd/0.83) with ESMTPA; Sun, 03 May 2015 11:30:07 +0100 From: Dave To: freebsd-questions@freebsd.org Subject: Re: How to restore a USB drive converted to bootable Date: Sun, 03 May 2015 11:30:07 +0100 Message-ID: <1701096.lYLT1Yt70m@amd.asgard.uk> User-Agent: KMail/4.14.3 (FreeBSD/9.3-RELEASE-p13; KDE/4.14.3; amd64; ; ) In-Reply-To: <5545553F.50602@hiwaay.net> References: <5543FAA3.7050907@hiwaay.net> <20150503002420.fdcc9310.freebsd@edvax.de> <5545553F.50602@hiwaay.net> MIME-Version: 1.0 Content-Transfer-Encoding: 7Bit Content-Type: text/plain; charset="us-ascii" X-Gradwell-MongoId: 5545f8af.101bf-2e2-2 X-Gradwell-Auth-Method: mailbox X-Gradwell-Auth-Credentials: fbsd@pop3.dgmm.net X-BeenThere: freebsd-questions@freebsd.org X-Mailman-Version: 2.1.20 Precedence: list List-Id: User questions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Sun, 03 May 2015 10:31:16 -0000 On Saturday 02 May 2015 17:59:02 William A. Mahaffey III wrote: > On 05/02/15 17:30, Polytropon wrote: > > On Sat, 02 May 2015 17:23:13 -0453, William A. Mahaffey III wrote: > >> On 05/02/15 16:45, Polytropon wrote: > >>> On Sat, 02 May 2015 09:20:09 -0453, William A. Mahaffey III wrote: > >>>> On 05/02/15 09:06, Lowell Gilbert wrote: > >>>>> "William A. Mahaffey III" writes: > >>>>> > >>>>>> I am about to do some OS installs (NetBSD & OpenBSD, as it happens) on > >>>>>> boxen under construction. I would also like to use UBCD on a flash > >>>>>> drive to memcheck those boxen prior to installation. If I prep a USB > >>>>>> thumb drive as either a bootable UBCD drive or an over-the-WWW > >>>>>> installer, I wipe out the drive for its original use. Is there a way > >>>>>> to restore the drive back to its original functionality if I wanted to > >>>>> Is "wipe the drive and reformat" what you need to hear, or do you have > >>>>> more requirements that you haven't made clear? > >>>>> > >>>> Wipe & reformat, preferably from CLI under FBSD 9.3R-p13 for > >>>> convenience, is what I'm after. Clearly creating a bootable UBCD or > >>>> installer will wipe out whatever was > >>>> there before, so I just want to get back to 'virgin' USB drive. > >>> In that case, the command > >>> > >>> # dd if=/dev/zero of=/dev/da0 bs=1m count=1 > >>> > >>> should be fine. If there is any offending GPT metadata located > >>> at the end of the USB drive, estimate the size and also erase > >>> the last few MBs (use skip= to do so). There is no need to > >>> actually zero out the _whole_ drive. > >> *Aaaaaaaaaaaaaaahhhhh*, I wasn't sure about that (zero the whole drive), > >> thanks :-) .... > > There are only few significant "data zones" on the USB drive. > > The boot sector and partition table are located at the beginning, > > and _maybe_ GPT metadata at the end. Removing both makes the > > remaining bits and bytes practically useless (except when you > > take it to forensics, but you don't want to recover things > > anyway, so the result should work for you). > > > > However, if you want a USB drive "new" (as in "I just bought it > > from the shop, it's fresh out of the package!"), then you have > > to write a MSDOS (FAT) file system, install some crapware, some > > ridiculous "drivers", and "value added" software, maybe with > > some spying tools, malware, nagware, and non-working "encryption" > > tools. Add several partitions and make them smaller than the > > real size of the drive. And add a "Facebook" link. :-) > > > > > > > > I was thinking of dd-ing the 1st MB or 2 off into a file, then restoring > from that file when done, that would skip all the extra features you > mention ;-). Would 1 or 2 MB be enough to get all of the FS info ? I > wasn't aware you didn't have to zero everything out, that simplifies > things a fair bit .... > That might be enough if you are then going to put it in a drawer, not use it all, then restore those same few MB later. If you are planning on installing UBCD onto it in a some form of bootable filesystem them I'd suggest you need to DD *at least* the size of UBCD so you can restore any/all existing data. You could just DD the entire pendrive and pipe it through tar/gzip if you really want to be able to put back exactly as you found it since you don't really know exactly where on the drive the data is.