From owner-freebsd-fs@FreeBSD.ORG Tue Jul 12 17:35:55 2011 Return-Path: Delivered-To: freebsd-fs@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34]) by hub.freebsd.org (Postfix) with ESMTP id 2A6AC106566C for ; Tue, 12 Jul 2011 17:35:55 +0000 (UTC) (envelope-from artemb@gmail.com) Received: from mail-wy0-f182.google.com (mail-wy0-f182.google.com [74.125.82.182]) by mx1.freebsd.org (Postfix) with ESMTP id B57418FC0A for ; Tue, 12 Jul 2011 17:35:54 +0000 (UTC) Received: by wyg24 with SMTP id 24so574wyg.13 for ; Tue, 12 Jul 2011 10:35:53 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=gamma; h=mime-version:sender:in-reply-to:references:date :x-google-sender-auth:message-id:subject:from:to:cc:content-type; bh=4/AUM2D3n2p12MCH7b1AqpnbT5DVAvP0WX8AB7aQcDY=; b=G+kgSnZO7RivuSQ40Cbk+aAalmabe37miSGjmNYze0ZXKWSvmfjtQplPvN2kSl3IjA S3rZmCnsdvA54frBQBKDBw2QmiyVRjNTb5XLr5MV39DwBaQs0hKjShI5KA4EmTXCmSYU 35j11xjQqMEV8JoMVyNOno1lCb5chLMg0VXQI= MIME-Version: 1.0 Received: by 10.216.144.100 with SMTP id m78mr163651wej.55.1310492153410; Tue, 12 Jul 2011 10:35:53 -0700 (PDT) Sender: artemb@gmail.com Received: by 10.216.46.18 with HTTP; Tue, 12 Jul 2011 10:35:53 -0700 (PDT) In-Reply-To: <69E82BC1AF1E4F50B37119C4E614B190@multiplay.co.uk> References: <69E82BC1AF1E4F50B37119C4E614B190@multiplay.co.uk> Date: Tue, 12 Jul 2011 10:35:53 -0700 X-Google-Sender-Auth: ZKY-8YN0kxdpdJ8PHVJi_JBFTvM Message-ID: From: Artem Belevich To: Steven Hartland Content-Type: text/plain; charset=ISO-8859-1 Cc: freebsd-fs@freebsd.org Subject: Re: Forcing a full file read in ZFS even when checksum error encountered X-BeenThere: freebsd-fs@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: Filesystems List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Tue, 12 Jul 2011 17:35:55 -0000 On Tue, Jul 12, 2011 at 5:21 AM, Steven Hartland wrote: > I was wondering if anyone found a solution to the following thread > posted back in 2008. > http://lists.freebsd.org/pipermail/freebsd-fs/2008-February/004269.html > > I have a volume here which has a jpg reporting a checksum error > which refuses to read with cp giving a "Bad Address". > > Being a jpg is highly likely that a simple error will be recoverable > if I can read the data off. > > I'm also interested to see if this is an error or just a false > positive. Chances are that *is* an error somewhere. It could be HDD or bad RAM(at the time the write happened) or bad cabling, but the error is probably there. > > Has anyone found a solution to this? Maybe. See here: http://blogs.oracle.com/relling/entry/holy_smokes_a_holey_file Using that method you still would not get the bad block, but you may be able to recover data beyond it. If you really want to get access to the data that ZFS considers to be corrupted, you need to get close and personal with zdb. This blog post may be a good starting point: http://cuddletech.com/blog/?p=407 --Artem