From owner-freebsd-hackers@FreeBSD.ORG Fri Jan 13 14:40:09 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 2CBD716A422; Fri, 13 Jan 2006 14:40:09 +0000 (GMT) (envelope-from lists@jnielsen.net) Received: from ns1.jnielsen.net (ns1.jnielsen.net [69.55.238.237]) by mx1.FreeBSD.org (Postfix) with ESMTP id 78CD143D90; Fri, 13 Jan 2006 14:39:53 +0000 (GMT) (envelope-from lists@jnielsen.net) Received: from localhost (jn@ns1 [69.55.238.237]) (authenticated bits=0) by ns1.jnielsen.net (8.12.9p2/8.12.9) with ESMTP id k0DEdor5038408; Fri, 13 Jan 2006 06:39:52 -0800 (PST) (envelope-from lists@jnielsen.net) From: John Nielsen To: freebsd-hackers@freebsd.org Date: Fri, 13 Jan 2006 09:38:58 -0500 User-Agent: KMail/1.8.3 References: <200601120948.k0C9mcqR092895@www.kukulies.org> <20060112212337.GA80216@nargothrond.kdm.org> <20060113132915.GA6848@kukulies.org> In-Reply-To: <20060113132915.GA6848@kukulies.org> X-Face: #X5#Y*q>F:]zT!DegL3z5Xo'^MN[$8k\[4^3rN~wm=s=Uw(sW}R?3b^*f1Wu*.<=?utf-8?q?of=5F4NrS=0A=09P*M/9CpxDo!D6?=)IY1w<9B1jB; tBQf[RU-R<,I)e"$q7N7 MIME-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: 7bit Content-Disposition: inline Message-Id: <200601130938.58932.lists@jnielsen.net> X-Virus-Scanned: ClamAV version 0.87.1, clamav-milter version 0.87 on ns1.jnielsen.net X-Virus-Status: Clean Cc: "Kenneth D. Merry" , Christoph Kukulies , Peter Jeremy 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: Fri, 13 Jan 2006 14:40:09 -0000 On Friday 13 January 2006 08:29 am, Christoph P. Kukulies wrote: > On Thu, Jan 12, 2006 at 02:23:37PM -0700, Kenneth D. Merry wrote: > > > 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.) > > I was able to recover. The 0.99999980 copy of my damaged disk to the > identical new one, using > > recoverdisk /dev/ad2 /dev/ad3 > > turned out to have been successful. The program was still trying to > improve the result but I didn't see any increase of recoverd block, so I > terminated it. > > Just for the record: Before I wanted to give back in my faulty disk > to my computer supplier as a case for warranty, I zeroed out the faulty > disk. > > dd if=/dev/zero of=/dev/ad2 bs=1m > > It took half an hour to zero out the 80GB. Transferrate 44 MB/s? > And not a single error ? Or is this normal? > > Then I tried to read back > > dd if=/dev/ad2 of=/dev/zero bs=2m > > Yes, just for the fun I said 2m blocksiye. And now we come back > to FreeBSD contents: > > The system froze at this command (FreeBSD 5.2.1 on that machine) I don't know if this is why the system froze, but /dev/zero is probably not a useful output device. You could use of=/dev/null just to see if the disk reads succeed w/o errors. I've also done "cmp /dev/adX /dev/zero" before, but you don't have any control over how the disk reads are handled that way. JN