From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 9E7FBEB64DC for ; Thu, 6 Jul 2023 07:07:22 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233160AbjGFHHU (ORCPT ); Thu, 6 Jul 2023 03:07:20 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:36004 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233511AbjGFHHS (ORCPT ); Thu, 6 Jul 2023 03:07:18 -0400 Received: from mout.gmx.net (mout.gmx.net [212.227.17.20]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id A64E11732 for ; Thu, 6 Jul 2023 00:07:12 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=gmx.com; s=s31663417; t=1688627228; x=1689232028; i=quwenruo.btrfs@gmx.com; bh=1hKteCVdGVtrDntB3mKq0OQKQNzIf4gRIAKpMTgwJ6U=; h=X-UI-Sender-Class:Date:Subject:To:Cc:References:From:In-Reply-To; b=XITLdigNzuK/ngq0Do1wxg2GssksMqthhwFQ8leGSmR78uInyh3MZeeWXP3O69SYxuHqav4 hrzTxXhu+Hji6g8TCWFeepnmAPq3YHTywhDc6EC//U1e/80UVtIw6XGyCXefD75WgaGeNFWhp lqiXo1rYNvSq299pNSPFiNveZ1cGKIEP5m/e5/M5UKNeWCf7ZHnbG9Da+QplKldDFryu5HSIN HWuUCewKOnTyyYLcsbHttc0euCCkXKZ5NGKwukfBWBoLojWIG06GYpxlmPOjlePZIPecVc0Xw 1e8HwMpqfLh99I7SRe6iSOklEeHVDIhBoyNQzLhdClrTgjMJi1PQ== X-UI-Sender-Class: 724b4f7f-cbec-4199-ad4e-598c01a50d3a Received: from [0.0.0.0] ([149.28.201.231]) by mail.gmx.net (mrgmx105 [212.227.17.174]) with ESMTPSA (Nemesis) id 1MdNcG-1piFNU0Jc0-00ZOSL; Thu, 06 Jul 2023 09:07:08 +0200 Message-ID: <5e5941b0-bd9e-e64a-251b-0e90688378d6@gmx.com> Date: Thu, 6 Jul 2023 15:07:04 +0800 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:102.0) Gecko/20100101 Thunderbird/102.12.0 Subject: Re: question to btrfs scrub Content-Language: en-US To: Andrei Borzenkov Cc: Bernd Lentes , Qu Wenruo , linux-btrfs References: <8a3d7ad6-0ddb-3160-eece-8d6228b9c0a6@gmx.com> <3d208b62-efc2-afe4-e928-986dc4c53936@gmx.com> <80136f6f-0575-58e8-ea8d-7053c8af4db0@suse.com> <11a9ec6a-7469-fdba-4375-c24e8ea5f7fb@gmx.com> From: Qu Wenruo In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: quoted-printable X-Provags-ID: V03:K1:FlbwfgX00+xqj+Cg5xGGLDDWDvwgsjxJwKJfOY9vyrVAkDAOF/2 bbkZDB7nkl9FpCmAKIPze0TJ0aHba6u0XoCFkBtEonnvvnIlTxSPKiSONURdH5sd6ZdcUES LtmvSLvnRG0ozZ5t+SFr4UKYO1r/t48hyrGftKFvq70JZVXuh9E8onRtqDtfZz3wcZYVubS wmO/dpj8UWpy8s5oYx3eg== UI-OutboundReport: notjunk:1;M01:P0:fZhJAX2Xs4Q=;WXpVf3hSiZ5TXSTfMNpBB0k3RJs 1BlzwQfL69Yqf9PVS9OJsuDTvzZZxUBp6swj1MfMnRH34eV2oQmaTpNWJrTC8cMzAOaYj9h6v uJQGm1L2og+cE/0ft0LAEJCipyveuGMlalJQFuvIp/M3VVybeuHogTANTggkseK9N9bi+2tnC NLg9PfGvSQXmf5MGXEIgcGBxjxScKRwzjsgGYP+qFaDoz67f7gPfQOxP9K5D1FQmIiVp1PpuW wmWSuMiob2GWWjJoklmzm0yaSp94QVexW3buErmo37HzeMZU25w7wL1mDSBg05TtDQh+utHTu EVCNd1Jh19UxdhMnWsDHC9Zz6XwV/LV4Akf9fgHRmMfAZR1BSQUterPVGRL7gSrA2D9ShCAW2 J/yIHKx523zu+S+xA3a6PAZmhy+o9uxoZVZTHtuqDQwC8AdehYibQKZ3jf+vyfIgDDTG98A3E 5E0YPVeRBc7hFuWjcmD493M8yzToVmhF9M0lGlwwDWXumNEVOi6plM0swQBupOJypuzAOAEXw 3pPDuYjgM0Zw5GKU4ckaNh8zjrh37zwHV1Xr6XxkNR4YTZHQSjIJ2mOuYIpztavUg+OUz1Fp/ 9xuBjF+4Ny8jyN3o/X8gVafi5jl9N1r3mmHayxN0eGeCHbhsx9j1c9migT6+62lA0Cj7NCiOn espZ8mjo4vhGxDLKA35H8HfBtdtLk7P8LlPt7uVpxfbEl7z43E1FwGDGlyrAYSTEsmT4Q2NZD SVMrKx/4uwnpfWOGWQQXqwLxHSAclgm8YlL0yHH2pM2Mcm0m5KUQ9rZkysdPNwtKROFnp8VbI XQuI9zpGwMCIfHRqvkCNc1e1D7Jq/hKKQxqZHUJU3urszxoQ7jQHKG8ueOHLRpg7Y7k50lw72 lwu3LM433Gedj9QErQx9Yp9CVdgHsAtKuzfwc4SQxluJn6auiVUH1Vc1bHKOL73h+i+Saj1uA jv52zPtQr3Ia5egVGY6IRno00SU= Precedence: bulk List-ID: X-Mailing-List: linux-btrfs@vger.kernel.org On 2023/7/6 15:04, Andrei Borzenkov wrote: > On Thu, Jul 6, 2023 at 9:22=E2=80=AFAM Qu Wenruo wrote: >> >> In your case, since you're already using LVM, thus I believe the fs is >> using default profiles (DUP for meta, SINGLE for data), thus there woul= d >> be no extra copy to recover from. >> >> So there is really error detection functionality lost if go nodatasum. >> > > You probably mean, "error *correction*". Oh, my bad, it's indeed error *correction*. Thanks, Qu > Error detection will > certainly be lost. And error detection is certainly useful to detect > data corruption (that is not usually possible using traditional > filesystems). Yes, it will not be possible to correct these errors on > btrfs level without redundancy.