From owner-freebsd-chat@FreeBSD.ORG Sun Jul 8 11:56:39 2007 Return-Path: X-Original-To: freebsd-chat@freebsd.org Delivered-To: freebsd-chat@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [69.147.83.52]) by hub.freebsd.org (Postfix) with ESMTP id 7065C16A41F for ; Sun, 8 Jul 2007 11:56:39 +0000 (UTC) (envelope-from fb-chat@psconsult.nl) Received: from ps226.psconsult.nl (ps226.psconsult.nl [213.222.19.226]) by mx1.freebsd.org (Postfix) with ESMTP id 0309213C45A for ; Sun, 8 Jul 2007 11:56:38 +0000 (UTC) (envelope-from fb-chat@psconsult.nl) Received: from phuket.psconsult.nl (localhost [127.0.0.1]) by phuket.psconsult.nl (8.13.1/8.13.1) with ESMTP id l68BOEw8027189 for ; Sun, 8 Jul 2007 13:24:14 +0200 (CEST) (envelope-from fb-chat@psconsult.nl) Received: (from paul@localhost) by phuket.psconsult.nl (8.13.1/8.13.1/Submit) id l68BOEBB027188 for freebsd-chat@freebsd.org; Sun, 8 Jul 2007 13:24:14 +0200 (CEST) (envelope-from fb-chat@psconsult.nl) Date: Sun, 8 Jul 2007 13:24:13 +0200 From: Paul Schenkeveld To: freebsd-chat@freebsd.org Message-ID: <20070708112413.GA27077@psconsult.nl> Mail-Followup-To: freebsd-chat@freebsd.org References: <669580.92520.qm@web58104.mail.re3.yahoo.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <669580.92520.qm@web58104.mail.re3.yahoo.com> User-Agent: Mutt/1.5.6i Subject: Re: compressed HDD image using dd...clearing unused blocks X-BeenThere: freebsd-chat@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: Non technical items related to the community List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Sun, 08 Jul 2007 11:56:39 -0000 On Sat, Jul 07, 2007 at 10:28:01PM -0700, Michael Eubanks wrote: > Hello all, > > I am updating a system that has been around for some > time now. I would like to make a compressed disk > image after the final setup is complete, although, I'm > guessing that the unused blocks will not allow me to > compress the image as well as I could with a > previously clean disk (considering the disk has been > in use for some time now). Is there a way to do this > - zero out unused blocks to optimize compression? I > generally do this with Windows machines using the > cipher command (killing cipher after it has finished > writing zeroes). After running cipher I use dd to > create a compressed HDD image for later use. I'd like > to be able to do the same with FreeBSD. What about: # dd < /dev/zero > BIG_EMPTY_FILE bs=128k # rm BIG_EMPTY_FILE Comes close to what you want, only a couple of indirect blocks are not zeroed this way but the majority of unused blocks will be. > -Michael S. Eubanks > mse0206@yahoo.com -- Paul Schenkeveld