From owner-freebsd-hackers@FreeBSD.ORG Thu Jan 12 21:23:46 2006 Return-Path: X-Original-To: freebsd-hackers@freebsd.org Delivered-To: freebsd-hackers@freebsd.org Received: from mx1.FreeBSD.org (mx1.freebsd.org [216.136.204.125]) by hub.freebsd.org (Postfix) with ESMTP id DB7E216A41F for ; Thu, 12 Jan 2006 21:23:46 +0000 (GMT) (envelope-from ken@nargothrond.kdm.org) Received: from nargothrond.kdm.org (nargothrond.kdm.org [70.56.43.81]) by mx1.FreeBSD.org (Postfix) with ESMTP id 4DE6443D48 for ; Thu, 12 Jan 2006 21:23:41 +0000 (GMT) (envelope-from ken@nargothrond.kdm.org) Received: from nargothrond.kdm.org (localhost [127.0.0.1]) by nargothrond.kdm.org (8.13.4/8.12.11) with ESMTP id k0CLNcYD080286; Thu, 12 Jan 2006 14:23:38 -0700 (MST) (envelope-from ken@nargothrond.kdm.org) Received: (from ken@localhost) by nargothrond.kdm.org (8.13.4/8.12.5/Submit) id k0CLNbHN080285; Thu, 12 Jan 2006 14:23:37 -0700 (MST) (envelope-from ken) Date: Thu, 12 Jan 2006 14:23:37 -0700 From: "Kenneth D. Merry" To: Peter Jeremy Message-ID: <20060112212337.GA80216@nargothrond.kdm.org> References: <200601120948.k0C9mcqR092895@www.kukulies.org> <20060112211300.GB13244@cirb503493.alcatel.com.au> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20060112211300.GB13244@cirb503493.alcatel.com.au> User-Agent: Mutt/1.4.2i X-Virus-Scanned: ClamAV 0.87.1/1239/Thu Jan 12 04:36:22 2006 on nargothrond.kdm.org X-Virus-Status: Clean Cc: Christoph Kukulies , freebsd-hackers@freebsd.org Subject: Re: increasing dd disk to disk transfer rate X-BeenThere: freebsd-hackers@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: Technical Discussions relating to FreeBSD List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Thu, 12 Jan 2006 21:23:47 -0000 On Fri, Jan 13, 2006 at 08:13:00 +1100, Peter Jeremy wrote: > On Thu, 2006-Jan-12 10:48:38 +0100, Christoph Kukulies wrote: > >dd if=/dev/ad2 of=/dev/ad3 conv=noerror > > > >The process is running now since yesterday evening and it is at 53 MB > >at a transfer rate of about 1.1 MB/s. > > > >In case the the result being unusable I would like to find a way to make this > >copying faster. > > Note that whilst increasing the DD blocksize will speed up the > transfer, it will also increase the amount of collateral damage when a > hard error occurs. If you rummage around the ports or tools tree, > you'll find a utility (its name escapes me but I believe it was > written by phk) that is designed to do disk-to-disk recovery - it > copys data in big slabs until it gets an error and then works around > the faulty area block by block. It's called 'recoverdisk', and is in src/tools/tools/recoverdisk. I used it to copy a friend's hard drive, and it worked well. (Although the supposedly 'bad' disk didn't turn out to have any bad sectors.) Ken -- Kenneth Merry ken@FreeBSD.ORG