From owner-freebsd-questions@FreeBSD.ORG Wed Sep 30 20:40:37 2009 Return-Path: Delivered-To: freebsd-questions@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34]) by hub.freebsd.org (Postfix) with ESMTP id 5C529106568F for ; Wed, 30 Sep 2009 20:40:37 +0000 (UTC) (envelope-from freebsd@edvax.de) Received: from mx01.qsc.de (mx01.qsc.de [213.148.129.14]) by mx1.freebsd.org (Postfix) with ESMTP id 16A078FC1E for ; Wed, 30 Sep 2009 20:40:36 +0000 (UTC) Received: from r55.edvax.de (port-92-195-71-245.dynamic.qsc.de [92.195.71.245]) by mx01.qsc.de (Postfix) with ESMTP id 7CFA73D708; Wed, 30 Sep 2009 22:40:36 +0200 (CEST) Received: from r55.edvax.de (localhost [127.0.0.1]) by r55.edvax.de (8.14.2/8.14.2) with SMTP id n8UKeYlD001529; Wed, 30 Sep 2009 22:40:35 +0200 (CEST) (envelope-from freebsd@edvax.de) Date: Wed, 30 Sep 2009 22:40:34 +0200 From: Polytropon To: Jerry McAllister Message-Id: <20090930224034.3c960afc.freebsd@edvax.de> In-Reply-To: <20090930153058.GC27266@gizmo.acns.msu.edu> References: <4AC29BE6.4000505@videotron.ca> <20090930023051.cff2b0b4.freebsd@edvax.de> <4AC2C104.7090206@videotron.ca> <20090930050805.7f9d7252.freebsd@edvax.de> <20090930153058.GC27266@gizmo.acns.msu.edu> Organization: EDVAX X-Mailer: Sylpheed 2.4.7 (GTK+ 2.12.1; i386-portbld-freebsd7.0) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Cc: PJ , freebsd-questions@freebsd.org Subject: Re: backups & cloning 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: Wed, 30 Sep 2009 20:40:37 -0000 About the dd method: On Wed, 30 Sep 2009 11:30:58 -0400, Jerry McAllister wrote: > It can be used, but it is not a good way to do it. For regular backups or even for cloning, it's not very performant, I agree. I'm mostly using this method for forensic purposes, when I need a copy of a media (a whole disk, one slice or a particular partition) to toy around with, so I don't mess up the original data. > That is because it copies sector by sector and the new > disk/filesystem may not match the old exactly. That's a known problem. Another problem is time complexity. The dd program does copy everything - even the unused disk blocks (which don't need to be copied). This makes this process often last very long. > Besides > when it is newly written on a file by file basis, it can > be more efficiently laid out and accomodate any changes in > size and sector addressing. dd cannot do that. That's true. This is the point where tools like cpdup and rsync come into mind (according to creating backups or clones). -- Polytropon Magdeburg, Germany Happy FreeBSD user since 4.0 Andra moi ennepe, Mousa, ...