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 454AD138378 for ; Tue, 8 Jan 2013 20:58:46 +0000 (UTC) Received: from pigeon.gentoo.org (localhost [127.0.0.1]) by pigeon.gentoo.org (Postfix) with SMTP id A948CE06C2; Tue, 8 Jan 2013 20:58:35 +0000 (UTC) Received: from mail-we0-f179.google.com (mail-we0-f179.google.com [74.125.82.179]) (using TLSv1 with cipher ECDHE-RSA-RC4-SHA (128/128 bits)) (No client certificate requested) by pigeon.gentoo.org (Postfix) with ESMTPS id 233E821C030 for ; Tue, 8 Jan 2013 20:57:10 +0000 (UTC) Received: by mail-we0-f179.google.com with SMTP id r6so693078wey.24 for ; Tue, 08 Jan 2013 12:57:09 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20120113; h=mime-version:in-reply-to:references:date:message-id:subject:from:to :content-type; bh=YYmlB7bUFYazCFnK2ayLKS9GzO0i37W2+Q3Pp3udsuQ=; b=QtgW7g6Dwrf7atIMmuKH/kUldhRaxZW1Nuqg5ipojEJJ24uHlwE99bfkl/DjCrQZ/x GhQb5G7VPspuRplv5frAbejizwLBUluMqJ2uSdlBKAzQwTR94JK0Hbl8o0beprFkg4iP J8Epb1jm8Hh6tLrlJ4NtAsUw+Q1cd447ACNliVSrU71muC6qkzO4knDFfxS3FVTnpEOE wycZpZNg1xLw4ewmGvz076uVhVIML9tHwrIP2x/4VoYMr8S7yKy7vVbYauF/Kp0W4BzX K7698vHcJ5P7zBbKWt1v0Ms0uvJSmJr/+Q5ANvSqLmlrQguzwRF5oerhbXkc4cpeS2+e p35w== 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 Received: by 10.194.238.5 with SMTP id vg5mr103638898wjc.40.1357678629776; Tue, 08 Jan 2013 12:57:09 -0800 (PST) Received: by 10.216.255.71 with HTTP; Tue, 8 Jan 2013 12:57:09 -0800 (PST) In-Reply-To: <50EC6E31.7030101@binarywings.net> References: <50EB2BF7.4040109@binarywings.net> <20130108012016.2f02c68c@khamul.example.com> <50EBCA77.8030603@binarywings.net> <3613897.q2tncFpUrH@localhost> <50EC6E31.7030101@binarywings.net> Date: Tue, 8 Jan 2013 15:57:09 -0500 Message-ID: Subject: Re: [gentoo-user] OT: Fighting bit rot From: Joshua Murphy To: gentoo-user@lists.gentoo.org Content-Type: text/plain; charset=UTF-8 X-Archives-Salt: 59aff23c-e646-47fc-9db7-59e5ebeebb70 X-Archives-Hash: e47abab34f924d0ac92ac3030f734da2 On Tue, Jan 8, 2013 at 2:06 PM, Florian Philipp wrote: > Am 08.01.2013 18:35, schrieb Volker Armin Hemmann: >> Am Dienstag, 8. Januar 2013, 08:27:51 schrieb Florian Philipp: >>> Am 08.01.2013 00:20, schrieb Alan McKinnon: >>>> On Mon, 07 Jan 2013 21:11:35 +0100 >>>> >>>> Florian Philipp wrote: >>>>> Hi list! >>>>> >>>>> I have a use case where I am seriously concerned about bit rot [1] >>>>> and I thought it might be a good idea to start looking for it in my >>>>> own private stuff, too. >>> >>> [...] >>> >>>>> [1] http://en.wikipedia.org/wiki/Bit_rot > [...] >>>> If you mean disk file corruption, then doing it file by file is a >>>> colossal waste of time IMNSHO. You likely have >1,000,000 files. Are >>>> you really going to md5sum each one daily? Really? >>> >>> Well, not daily but often enough that I likely still have a valid copy >>> as a backup. >> >> and who guarantees that the backup is the correct file? >> > > That's why I wanted to store md5sum (or sha2sums). > >> btw, the solution is zfs and weekly scrub runs. >> > > Seems so. > And, while it's not exceptionally likely, there's always a possibility that the checksum table, rather than the file being checked itself, is the location of the corruption, meaning you have to verify that as well when discrepancies occur. The likelihood of the perfect few bits flipping to match the corrupted data with a corrupted hash, within the time between checks, however, I would think is low enough to gamble on never seeing it in a reasonable lifetime. -- Poison [BLX] Joshua M. Murphy