Debian Bug report logs - #410209
conv=noerror poorly documented

Full log

🔗 View this message in rfc822 format

X-Loop: [email protected]
Subject: Bug#410209: conv=noerror poorly documented
Reply-To: Jim Meyering <[email protected]>, [email protected]
Resent-From: Jim Meyering <[email protected]>
Resent-To: [email protected]
Resent-CC: Michael Stone <[email protected]>
Resent-Date: Sat, 24 May 2008 06:27:02 +0000
Resent-Message-ID: <[email protected]>
Resent-Sender: [email protected]
X-Debian-PR-Message: followup 410209
X-Debian-PR-Package: coreutils
X-Debian-PR-Keywords: 
X-Debian-PR-Source: coreutils
Received: via spool by [email protected] id=B410209.121161031116353
          (code B ref 410209); Sat, 24 May 2008 06:27:02 +0000
Received: (at 410209) by bugs.debian.org; 24 May 2008 06:25:11 +0000
X-Spam-Checker-Version: SpamAssassin 3.1.4-bugs.debian.org_2005_01_02 
	(2006-07-26) on rietz.debian.org
X-Spam-Level: 
X-Spam-Status: No, score=-6.9 required=4.0 tests=BAYES_00,FOURLA,
	HAS_BUG_NUMBER,MURPHY_DRUGS_REL8 autolearn=no 
	version=3.1.4-bugs.debian.org_2005_01_02
Received: from mx.meyering.net ([82.230.74.64])
	by rietz.debian.org with esmtp (Exim 4.63)
	(envelope-from <[email protected]>)
	id 1JznBn-0004EY-68
	for [email protected]; Sat, 24 May 2008 06:25:11 +0000
Received: by rho.meyering.net (Acme Bit-Twister, from userid 1000)
	id 4EB6D5519F; Sat, 24 May 2008 08:25:09 +0200 (CEST)
From: Jim Meyering <[email protected]>
To: Lucas Nussbaum <[email protected]>, [email protected]
Cc: [email protected]
In-Reply-To: <[email protected]> (Lucas Nussbaum's
	message of "Fri, 23 May 2008 23:43:48 +0200")
References: <[email protected]>
	<[email protected]>
Date: Sat, 24 May 2008 08:25:09 +0200
Message-ID: <[email protected]>
Lines: 49
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii

Lucas Nussbaum <[email protected]> wrote:
> Debian bug #410209 sounds like a sensible request for a doc (info page)
> improvement.
>
> Could you take a quick look?

Hi Lucas,
Thanks for the heads-up.
And thanks to Jiri for the report!

Yes, that will make a fine improvement.
Jiri, do you feel like preparing a patch?
It'd be good to include the note about, and sample output from fsck, too.
If so, instructions for contributing are here:

  http://git.sv.gnu.org/gitweb/?p=coreutils.git;a=blob;f=HACKING;hb=HEAD

If not, maybe Lucas will.

You may want to consider using ddrescue next time:
  http://www.gnu.org/software/ddrescue/ddrescue.html

> On 09/02/07 at 02:42 +1100, Jiri Baum wrote:
>> Package: coreutils
>> Version: 5.97-5
>>
>> The documentation for the dd(1) 'noerror' keyword does not make it clear what
>> happens to the blocks in which read errors occurred (or that this depends on
>> the apparently-unrelated 'sync' keyword).
>>
>> I would suggest that the current text "continue after read errors" (in the man
>> and info pages) be expanded to indicate that without 'sync', input blocks
>> with errors are dropped; with 'sync', whatever was read of input blocks with
>> errors is padded to ibs and written.
>>
>> (If I understand the source correctly...)
>>
>> For example, to read data off a failing disk, one should use:
>>   dd if=/dev/hdXY of=/filename.disk conv=noerror,sync
>>
>> Omitting the 'sync' is a problem, since all offsets will be off from the first
>> read error onwards and the size of the disk image will not match the size
>> recorded in the superblock. This will lead to the following message from fsck
>> when attempting to repair the disk image:
>>
>> The filesystem size (according to the superblock) is X blocks
>> The physical size of the device is Y blocks
>> Either the superblock or the partition table is likely to be corrupt!
>> Abort<y>?

Send a report that this bug log contains spam.