From owner-freebsd-questions@FreeBSD.ORG Fri Oct 31 11:02:01 2008 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 EBCD81065676 for ; Fri, 31 Oct 2008 11:02:01 +0000 (UTC) (envelope-from jdc@koitsu.dyndns.org) Received: from QMTA01.westchester.pa.mail.comcast.net (qmta01.westchester.pa.mail.comcast.net [76.96.62.16]) by mx1.freebsd.org (Postfix) with ESMTP id 984A08FC24 for ; Fri, 31 Oct 2008 11:02:01 +0000 (UTC) (envelope-from jdc@koitsu.dyndns.org) Received: from OMTA03.westchester.pa.mail.comcast.net ([76.96.62.27]) by QMTA01.westchester.pa.mail.comcast.net with comcast id ZNXN1a00B0bG4ec51P20ip; Fri, 31 Oct 2008 11:02:00 +0000 Received: from koitsu.dyndns.org ([69.181.141.110]) by OMTA03.westchester.pa.mail.comcast.net with comcast id ZP1z1a00b2P6wsM3PP20dh; Fri, 31 Oct 2008 11:02:00 +0000 X-Authority-Analysis: v=1.0 c=1 a=QycZ5dHgAAAA:8 a=bjNuHRgfvkh4-F6peDAA:9 a=YVkm4TDcygXPd8l1xhrnmE5bNkwA:4 a=EoioJ0NPDVgA:10 a=LY0hPdMaydYA:10 Received: by icarus.home.lan (Postfix, from userid 1000) id AB181C9419; Fri, 31 Oct 2008 04:01:59 -0700 (PDT) Date: Fri, 31 Oct 2008 04:01:59 -0700 From: Jeremy Chadwick To: Christoph Kukulies Message-ID: <20081031110159.GA30244@icarus.home.lan> References: <490AC650.3000904@kukulies.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <490AC650.3000904@kukulies.org> User-Agent: Mutt/1.5.18 (2008-05-17) Cc: freebsd-questions@freebsd.org Subject: Re: fastest raw device copy? X-BeenThere: freebsd-questions@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: User questions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Fri, 31 Oct 2008 11:02:02 -0000 On Fri, Oct 31, 2008 at 09:48:16AM +0100, Christoph Kukulies wrote: > Hi list, > > I'm considering using a bootable USB stick with FreeBSD to perform a > backup of my notebooks' > 500 GB hard disk to a physically identical (same make, same type, same > size) hard disk attached to USB. > > What would be the fastest way to do that sector by sector copy? I'm > using dd right now, > > dd if=/dev/ad0 of=/dev/da0 bs=10000000 > > but maybe there is a utility which does this faster or a larger buffer > size? Probably the limit will be > the USB 2.0 bus speed anyway? In general, what you're doing is correct for a block copy. There is nothing (that I know of) which is faster; you're copying 500GB of data (including the unused portion -- you *did* ask for a block copy), and this takes a long time. Be patient. On the flip side, your blocksize (bs) there is quite high for no good reason. I'd pick something more like bs=64k or bs=128k. The default (512) is too small for what you want, but 10MBytes is silly. -- | Jeremy Chadwick jdc at parodius.com | | Parodius Networking http://www.parodius.com/ | | UNIX Systems Administrator Mountain View, CA, USA | | Making life hard for others since 1977. PGP: 4BD6C0CB |