From owner-freebsd-hackers@FreeBSD.ORG Thu Jan 12 18:14:35 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 C926816A41F for ; Thu, 12 Jan 2006 18:14:35 +0000 (GMT) (envelope-from anderson@centtech.com) Received: from mh1.centtech.com (moat3.centtech.com [207.200.51.50]) by mx1.FreeBSD.org (Postfix) with ESMTP id 68E3943D48 for ; Thu, 12 Jan 2006 18:14:34 +0000 (GMT) (envelope-from anderson@centtech.com) Received: from [10.177.171.220] (neutrino.centtech.com [10.177.171.220]) by mh1.centtech.com (8.13.1/8.13.1) with ESMTP id k0CIETEZ086604; Thu, 12 Jan 2006 12:14:29 -0600 (CST) (envelope-from anderson@centtech.com) Message-ID: <43C69C86.6000707@centtech.com> Date: Thu, 12 Jan 2006 12:14:30 -0600 From: Eric Anderson User-Agent: Mozilla Thunderbird 1.0.7 (X11/20060110) X-Accept-Language: en-us, en MIME-Version: 1.0 To: Bakul Shah References: <200601121756.k0CHuDiv063356@gate.bitblocks.com> In-Reply-To: <200601121756.k0CHuDiv063356@gate.bitblocks.com> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit X-Virus-Scanned: ClamAV 0.87.1/1239/Thu Jan 12 05:36:22 2006 on mh1.centtech.com X-Virus-Status: Clean Cc: freebsd-hackers@freebsd.org, Ivan Voras 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 18:14:35 -0000 Bakul Shah wrote: >>Bakul Shah wrote: >> >> >>>>In the last episode (Jan 12), Christoph Kukulies said: >>>> >>>> >>>>dd if=/dev/ad2 conv=noerror,sync bs=64k | dd of=/dev/ad3 bs=64k >>>> >>>> >>>So now on the new disk he has files with random blocks of >>>zeroes and *no* error indication of which files are so >>>trashed. This is asking for trouble. Silent erros are >>>worse. >>> >>>He ought to do a file level copy, not disk level copy on >>>unix. That way he knows *which* files are trashed and can do >>> >>> >>The problem is, FreeBSD panics when it encounters bad sectors in >>filesystem metadata. I had the same situation ~a month ago and gave up, >>restoring from old backups. It will also probably panic on corrupted or >>zeroed metadata, but at least it's on a readable disk... >> >> > >Good point. Would fsdb help? If not someone ought to extend it. > > I think after the dd is done, fsck should be run against the affected filesystems, which should take care of most of the issues. The OP's question was how to make dd faster, not really how to get the data across safely. :) Eric -- ------------------------------------------------------------------------ Eric Anderson Sr. Systems Administrator Centaur Technology Anything that works is better than anything that doesn't. ------------------------------------------------------------------------