From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from lists.gentoo.org (pigeon.gentoo.org [208.92.234.80]) by finch.gentoo.org (Postfix) with ESMTP id 1F698138370 for ; Tue, 8 Jan 2013 16:18:29 +0000 (UTC) Received: from pigeon.gentoo.org (localhost [127.0.0.1]) by pigeon.gentoo.org (Postfix) with SMTP id B4D5E21C088; Tue, 8 Jan 2013 16:18:13 +0000 (UTC) Received: from out5-smtp.messagingengine.com (out5-smtp.messagingengine.com [66.111.4.29]) (using TLSv1 with cipher ADH-AES256-SHA (256/256 bits)) (No client certificate requested) by pigeon.gentoo.org (Postfix) with ESMTPS id 097FF21C045 for ; Tue, 8 Jan 2013 16:16:43 +0000 (UTC) Received: from compute4.internal (compute4.nyi.mail.srv.osa [10.202.2.44]) by gateway1.nyi.mail.srv.osa (Postfix) with ESMTP id 5B42620D38 for ; Tue, 8 Jan 2013 11:16:43 -0500 (EST) Received: from frontend2.nyi.mail.srv.osa ([10.202.2.161]) by compute4.internal (MEProxy); Tue, 08 Jan 2013 11:16:43 -0500 DKIM-Signature: v=1; a=rsa-sha1; c=relaxed/relaxed; d=binarywings.net; h=message-id:date:from:mime-version:to:subject:references :in-reply-to:content-type; s=mesmtp; bh=AdZacrqKM5FPpEK8CsxQT2LC wnI=; b=PwBrEdBmDhH2eXrUnlz8gDAcqzyZ3R7AUPQvMvQDUmNcnvLRpegYFOMF uUjiU06MBTMTzUr4r+cGpFfDi9Hb/0S2GmmfLTUSGY7RC8Djx5uFYsDLdxrRpaKq diT87550qL4yUQcye6fP2lj2wUW8bATpYrZcV4XC7HPemzg8LUA= DKIM-Signature: v=1; a=rsa-sha1; c=relaxed/relaxed; d= messagingengine.com; h=message-id:date:from:mime-version:to :subject:references:in-reply-to:content-type; s=smtpout; bh=AdZa crqKM5FPpEK8CsxQT2LCwnI=; b=NmGJcb0hBOXheSuCIGDW0ydHngNS7QCJRCEQ nKEeymVTOPpVymqP98Ctq8cwPdwAzvQb0WJ4v3QGPnvj19I01dwVJst2nMo750Dm vOrzCH0nkDxz879+RgRLdIir0PhSXqVtcc97rRqw21Lm5Qfh/fB4cysAmZ/PiJ6N CnYyOpA= X-Sasl-enc: B/kX2SZtQBTBbfSkynz/nn+5cB5ZoKFMZl5D8QdZaJPw 1357661802 Received: from [192.168.5.18] (unknown [83.169.5.6]) by mail.messagingengine.com (Postfix) with ESMTPA id 41FA34827D9 for ; Tue, 8 Jan 2013 11:16:42 -0500 (EST) Message-ID: <50EC4660.5090208@binarywings.net> Date: Tue, 08 Jan 2013 17:16:32 +0100 From: Florian Philipp User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:10.0.11) Gecko/20121130 Thunderbird/10.0.11 Precedence: bulk List-Post: List-Help: List-Unsubscribe: List-Subscribe: List-Id: Gentoo Linux mail X-BeenThere: gentoo-user@lists.gentoo.org Reply-to: gentoo-user@lists.gentoo.org MIME-Version: 1.0 To: gentoo-user@lists.gentoo.org Subject: Re: [gentoo-user] OT: Fighting bit rot References: <50EB2BF7.4040109@binarywings.net> <20130108012016.2f02c68c@khamul.example.com> <50EBCA77.8030603@binarywings.net> <20130108095510.04f84040@khamul.example.com> In-Reply-To: <20130108095510.04f84040@khamul.example.com> X-Enigmail-Version: 1.3.5 Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="------------enig444B532553210A64E2A26AE4" X-Archives-Salt: 028303f7-a00a-4296-8e4c-7be7c25e1f10 X-Archives-Hash: af3f12c8dea3bc59a8c44cead79271b8 This is an OpenPGP/MIME signed message (RFC 2440 and 3156) --------------enig444B532553210A64E2A26AE4 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: quoted-printable Am 08.01.2013 08:55, schrieb Alan McKinnon: > On Tue, 08 Jan 2013 08:27:51 +0100 > Florian Philipp wrote: >=20 [...] >> >> As I said above, the point is that I need to detect the error as long >> as I still have a valid backup. Professional archive solutions do >> this on their own but I'm looking for something suitable for desktop >> usage. >=20 > rsync might be able to give you something close to what you want > easily >=20 > Use the -n switch for an rsync between your originals and the last > backup copy, and mail the output to yourself. Parse it looking for ">" > and "<" symbols and investigate why the file changed. >=20 > This strikes me as being a very easy solution that you could use > reliably with a suitable combination of options.=20 >=20 >=20 Hmm, good idea, albeit similar to the `md5sum -c`. Either tool leaves you with the problem of distinguishing between legitimate changes (i.e. a user wrote to the file) and decay. When you have completely static content, md5sum, rsync and friends are sufficient. But if you have content that changes from time to time, the number of false-positives would be too high. In this case, I think you could easily distinguish by comparing both file content and time stamps. Now, that of course introduces the problem that decay could occur in the same time frame as a legitimate change, thus masking the decay. To reduce this risk, you have to reduce the checking interval. Regards, Florian Philipp --------------enig444B532553210A64E2A26AE4 Content-Type: application/pgp-signature; name="signature.asc" Content-Description: OpenPGP digital signature Content-Disposition: attachment; filename="signature.asc" -----BEGIN PGP SIGNATURE----- Version: GnuPG v2.0.19 (GNU/Linux) Comment: Using GnuPG with Mozilla - http://enigmail.mozdev.org/ iEYEARECAAYFAlDsRmUACgkQqs4uOUlOuU8XmwCfX0XwrEwHFOo5KwJ0eA+Mkn7X 6uIAn0v7mosM/i0fIaMdtUkVMDLPg4Ud =kkSw -----END PGP SIGNATURE----- --------------enig444B532553210A64E2A26AE4--