Received: (at 42034) by debbugs.gnu.org; 24 Jun 2020 22:30:30 +0000 From debbugs-submit-bounces <at> debbugs.gnu.org Wed Jun 24 18:30:30 2020 Received: from localhost ([127.0.0.1]:39315 helo=debbugs.gnu.org) by debbugs.gnu.org with esmtp (Exim 4.84_2) (envelope-from <debbugs-submit-bounces <at> debbugs.gnu.org>) id 1joDuX-00020T-PM for submit <at> debbugs.gnu.org; Wed, 24 Jun 2020 18:30:30 -0400 Received: from havoc.proulx.com ([96.88.95.61]:35126) by debbugs.gnu.org with esmtp (Exim 4.84_2) (envelope-from <bob@HIDDEN>) id 1joDuV-0001t4-HG for 42034 <at> debbugs.gnu.org; Wed, 24 Jun 2020 18:30:28 -0400 Received: from joseki.proulx.com (localhost [127.0.0.1]) by havoc.proulx.com (Postfix) with ESMTP id EF8074A for <42034 <at> debbugs.gnu.org>; Wed, 24 Jun 2020 16:30:20 -0600 (MDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=proulx.com; s=dkim2048; t=1593037821; bh=aWOITAfKs2VLqlcsV5ybJL7BPJShaZrypBUV2lgvUHA=; h=Date:From:To:Subject:References:In-Reply-To:From; b=mph/XnOhTE3V5qEZ8ceS7CXmcG43rnu5/g9Jj1PO8boninNZf5HDjYrRYFPqqdfSY vltXOd79CeM0b/BVhp1V89GdyIpz5eZLvvNK0Bdu9fHQc1YOERzzTZRTkWGMmHNF+k S+VzXGkyo4YDYKfSqDoLVZrEhZyoq3CEBVJiqC6/HL3p9nLJP/wIZJ2zR3LBJpdaKJ fQscoct+yEPji416ZNKRjo91X6hBGJTda3+7ctEUdlI1K2Ibsx49hzX524dNWOZxZ2 5wpr/pAgs1oxcHfdLo2EXxZOWKBNJhe4/2vJtGtRcW2me2kTXd4AWw40Y1a9qI7MOd qcct0O5FzUwRw== Received: from hysteria.proulx.com (hysteria.proulx.com [192.168.230.119]) by joseki.proulx.com (Postfix) with ESMTP id E97AC21185 for <42034 <at> debbugs.gnu.org>; Wed, 24 Jun 2020 16:30:19 -0600 (MDT) Received: by hysteria.proulx.com (Postfix, from userid 1000) id 7878B2DC8B; Wed, 24 Jun 2020 16:30:18 -0600 (MDT) Date: Wed, 24 Jun 2020 16:30:18 -0600 From: Bob Proulx <bob@HIDDEN> To: 42034 <at> debbugs.gnu.org Subject: Re: bug#42034: option to truncate at end or should that be default? Message-ID: <20200624162015168087241@HIDDEN> References: <CALOnQv4E_Nv+drzXhCSmjQuP1xLKYK_hu5iv3hr1JCNvC2zOKw@HIDDEN> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <CALOnQv4E_Nv+drzXhCSmjQuP1xLKYK_hu5iv3hr1JCNvC2zOKw@HIDDEN> X-Spam-Score: 0.0 (/) X-Debbugs-Envelope-To: 42034 X-BeenThere: debbugs-submit <at> debbugs.gnu.org X-Mailman-Version: 2.1.18 Precedence: list List-Id: <debbugs-submit.debbugs.gnu.org> List-Unsubscribe: <https://debbugs.gnu.org/cgi-bin/mailman/options/debbugs-submit>, <mailto:debbugs-submit-request <at> debbugs.gnu.org?subject=unsubscribe> List-Archive: <https://debbugs.gnu.org/cgi-bin/mailman/private/debbugs-submit/> List-Post: <mailto:debbugs-submit <at> debbugs.gnu.org> List-Help: <mailto:debbugs-submit-request <at> debbugs.gnu.org?subject=help> List-Subscribe: <https://debbugs.gnu.org/cgi-bin/mailman/listinfo/debbugs-submit>, <mailto:debbugs-submit-request <at> debbugs.gnu.org?subject=subscribe> Errors-To: debbugs-submit-bounces <at> debbugs.gnu.org Sender: "Debbugs-submit" <debbugs-submit-bounces <at> debbugs.gnu.org> X-Spam-Score: -1.0 (-) L A Walsh wrote: > I allocated a large file of contiguous space (~3.6T), the size of a disk > image I was going to copy into it with 'dd'. I have the disk image > 'overwrite' the existing file, in place ... It's possible that you might want to be rescuing data from a failing disk or doing other surgery upon it. Therefore I want to mention ddrescue here. https://www.gnu.org/software/ddrescue/ Of course it all depends upon the use case but ddrescue is a good tool to have in the toolbox. It might be just the right tool. Take for example a RAID1 image on two failing drives that should be identical but both are reporting errors. If the failures do not overlap then ddrescue can be used to merge the successful reads from those two images producing one fully correct image. Bob
bug-coreutils@HIDDEN:bug#42034; Package coreutils.
Full text available.Received: (at 42034) by debbugs.gnu.org; 24 Jun 2020 20:07:30 +0000 From debbugs-submit-bounces <at> debbugs.gnu.org Wed Jun 24 16:07:30 2020 Received: from localhost ([127.0.0.1]:39191 helo=debbugs.gnu.org) by debbugs.gnu.org with esmtp (Exim 4.84_2) (envelope-from <debbugs-submit-bounces <at> debbugs.gnu.org>) id 1joBgA-0004PN-L9 for submit <at> debbugs.gnu.org; Wed, 24 Jun 2020 16:07:30 -0400 Received: from mail-out.m-online.net ([212.18.0.9]:48438) by debbugs.gnu.org with esmtp (Exim 4.84_2) (envelope-from <whitebox@HIDDEN>) id 1joBg6-0004PC-W4 for 42034 <at> debbugs.gnu.org; Wed, 24 Jun 2020 16:07:29 -0400 Received: from frontend01.mail.m-online.net (unknown [192.168.8.182]) by mail-out.m-online.net (Postfix) with ESMTP id 49sZ1n4SJnz1qs3l; Wed, 24 Jun 2020 22:07:25 +0200 (CEST) Received: from localhost (dynscan1.mnet-online.de [192.168.6.70]) by mail.m-online.net (Postfix) with ESMTP id 49sZ1n2rTCz1r56k; Wed, 24 Jun 2020 22:07:25 +0200 (CEST) X-Virus-Scanned: amavisd-new at mnet-online.de Received: from mail.mnet-online.de ([192.168.8.182]) by localhost (dynscan1.mail.m-online.net [192.168.6.70]) (amavisd-new, port 10024) with ESMTP id wDPbB4bNrctQ; Wed, 24 Jun 2020 22:07:24 +0200 (CEST) X-Auth-Info: 0m5nsxui9KTi1w+PNcJiGiIRhO3xIrqDIlhD3cyEjikRuu62ALyD14H270N3JrQo Received: from igel.home (ppp-46-244-162-219.dynamic.mnet-online.de [46.244.162.219]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.mnet-online.de (Postfix) with ESMTPSA; Wed, 24 Jun 2020 22:07:24 +0200 (CEST) Received: by igel.home (Postfix, from userid 1000) id BCD3F2C0B37; Wed, 24 Jun 2020 22:07:23 +0200 (CEST) From: Andreas Schwab <schwab@HIDDEN> To: L A Walsh <coreutils@HIDDEN> Subject: Re: bug#42034: option to truncate at end or should that be default? References: <CALOnQv4E_Nv+drzXhCSmjQuP1xLKYK_hu5iv3hr1JCNvC2zOKw@HIDDEN> X-Yow: Was my SOY LOAF left out in th'RAIN? It tastes REAL GOOD!! Date: Wed, 24 Jun 2020 22:07:23 +0200 In-Reply-To: <CALOnQv4E_Nv+drzXhCSmjQuP1xLKYK_hu5iv3hr1JCNvC2zOKw@HIDDEN> (L. A. Walsh's message of "Wed, 24 Jun 2020 12:56:41 -0700") Message-ID: <87h7v0ut1g.fsf@HIDDEN> User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/27.0.91 (gnu/linux) MIME-Version: 1.0 Content-Type: text/plain X-Spam-Score: -0.7 (/) X-Debbugs-Envelope-To: 42034 Cc: 42034 <at> debbugs.gnu.org X-BeenThere: debbugs-submit <at> debbugs.gnu.org X-Mailman-Version: 2.1.18 Precedence: list List-Id: <debbugs-submit.debbugs.gnu.org> List-Unsubscribe: <https://debbugs.gnu.org/cgi-bin/mailman/options/debbugs-submit>, <mailto:debbugs-submit-request <at> debbugs.gnu.org?subject=unsubscribe> List-Archive: <https://debbugs.gnu.org/cgi-bin/mailman/private/debbugs-submit/> List-Post: <mailto:debbugs-submit <at> debbugs.gnu.org> List-Help: <mailto:debbugs-submit-request <at> debbugs.gnu.org?subject=help> List-Subscribe: <https://debbugs.gnu.org/cgi-bin/mailman/listinfo/debbugs-submit>, <mailto:debbugs-submit-request <at> debbugs.gnu.org?subject=subscribe> Errors-To: debbugs-submit-bounces <at> debbugs.gnu.org Sender: "Debbugs-submit" <debbugs-submit-bounces <at> debbugs.gnu.org> X-Spam-Score: -1.7 (-) On Jun 24 2020, L A Walsh wrote: > A second option would be to truncate the file to the last position > written. $ truncate -r $src $dest Andreas. -- Andreas Schwab, schwab@HIDDEN GPG Key fingerprint = 7578 EB47 D4E5 4D69 2510 2552 DF73 E780 A9DA AEC1 "And now for something completely different."
bug-coreutils@HIDDEN:bug#42034; Package coreutils.
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To: bug-coreutils@HIDDEN Content-Type: multipart/alternative; boundary="00000000000098134805a8d9e0b4" Received-SPF: softfail client-ip=209.85.166.42; envelope-from=gsuite@HIDDEN; helo=mail-io1-f42.google.com X-detected-operating-system: by eggs.gnu.org: First seen = 2020/06/24 15:56:53 X-ACL-Warn: Detected OS = Linux 2.2.x-3.x [generic] [fuzzy] X-Spam_score_int: -21 X-Spam_score: -2.2 X-Spam_bar: -- X-Spam_report: (-2.2 / 5.0 requ) BAYES_00=-1.9, HTML_MESSAGE=0.001, RCVD_IN_DNSWL_NONE=-0.0001, RCVD_IN_MSPIKE_H2=-1, SPF_HELO_NONE=0.001, SPF_SOFTFAIL=0.665 autolearn=_AUTOLEARN X-Spam_action: no action X-Spam-Score: -1.3 (-) X-Debbugs-Envelope-To: submit X-BeenThere: debbugs-submit <at> debbugs.gnu.org X-Mailman-Version: 2.1.18 Precedence: list List-Id: <debbugs-submit.debbugs.gnu.org> List-Unsubscribe: <https://debbugs.gnu.org/cgi-bin/mailman/options/debbugs-submit>, <mailto:debbugs-submit-request <at> debbugs.gnu.org?subject=unsubscribe> List-Archive: <https://debbugs.gnu.org/cgi-bin/mailman/private/debbugs-submit/> List-Post: <mailto:debbugs-submit <at> debbugs.gnu.org> List-Help: <mailto:debbugs-submit-request <at> debbugs.gnu.org?subject=help> List-Subscribe: <https://debbugs.gnu.org/cgi-bin/mailman/listinfo/debbugs-submit>, <mailto:debbugs-submit-request <at> debbugs.gnu.org?subject=subscribe> Errors-To: debbugs-submit-bounces <at> debbugs.gnu.org Sender: "Debbugs-submit" <debbugs-submit-bounces <at> debbugs.gnu.org> X-Spam-Score: -2.3 (--) --00000000000098134805a8d9e0b4 Content-Type: text/plain; charset="UTF-8" I allocated a large file of contiguous space (~3.6T), the size of a disk image I was going to copy into it with 'dd'. I have the disk image 'overwrite' the existing file, in place using "conv=nocreat,notrunc" (among other switches) and that works with the final file still using max-sized 8GB extents. I realize that I _do_ want it to truncate the file to the actual size when done. The 'notrunc' switch doesn't work for this purpose as its meaning is overloaded (it really specifies multiple behaviors) both the non-truncation effect, as well as a directive to preserve any blocks not written during that specific invocation of 'dd'. A possible 3rd behavior arises from a vague definition of a block. Do they mean to preserve the data in the block, or do they mean to preserve the position of the block on disk? It seems they mean to preserve data, but whether or not that also preserves a place on disk isn't specified. There really needs to be something to specify that writes occur "in-place" such that no "_RE_-allocation" of blocks occurs (except to extend the file, if needed) A second option would be to truncate the file to the last position written. Maybe a oflag=overwrite, and a 'ftrunc' for 'final trunc' to the position of the final byte written? --00000000000098134805a8d9e0b4 Content-Type: text/html; charset="UTF-8" Content-Transfer-Encoding: quoted-printable <div dir=3D"ltr"><div class=3D"gmail_default" style=3D"font-family:monospac= e;font-size:large">I allocated a large file of contiguous space (~3.6T), th= e size of a disk image I was going to copy into it with 'dd'.=C2=A0= I have the disk image 'overwrite' the existing file, in place usin= g "conv=3Dnocreat,notrunc" (among other switches) and that works = with the final file still using max-sized 8GB extents.<br><br></div><div cl= ass=3D"gmail_default" style=3D"font-family:monospace;font-size:large">I rea= lize that I _do_ want it to truncate the file to the actual size when done.= <br><br></div><div class=3D"gmail_default" style=3D"font-family:monospace;f= ont-size:large">The 'notrunc' switch doesn't work for this purp= ose as its meaning is overloaded (it really specifies multiple behaviors) b= oth the non-truncation effect, as well as a directive to preserve any block= s not written during that specific invocation of 'dd'.=C2=A0 A poss= ible 3rd behavior arises from a vague definition of a block.=C2=A0 Do they = mean to preserve the data in the block, or do they mean to preserve the pos= ition of the block on disk?=C2=A0 It seems they mean to preserve data, but = whether or not that also preserves a place on disk isn't specified.<br>= <br></div><div class=3D"gmail_default" style=3D"font-family:monospace;font-= size:large">There really needs to be something to specify that writes occur= "in-place" such that no "_RE_-allocation" of blocks oc= curs (except to extend the file, if needed)=C2=A0 A second option would be = to truncate the file to the last position written.<br><br><br></div><div cl= ass=3D"gmail_default" style=3D"font-family:monospace;font-size:large">Maybe= a oflag=3Doverwrite, and a 'ftrunc' for 'final trunc' to t= he position of the final byte written?<br><br><br></div><div class=3D"gmail= _default" style=3D"font-family:monospace;font-size:large"><br><br><br></div= ></div> --00000000000098134805a8d9e0b4--
L A Walsh <coreutils@HIDDEN>:bug-coreutils@HIDDEN.
Full text available.bug-coreutils@HIDDEN:bug#42034; Package coreutils.
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