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 X-Spam-Level: X-Spam-Status: No, score=-0.8 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 45FE6C432C0 for ; Thu, 28 Nov 2019 01:23:46 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 1903C206E0 for ; Thu, 28 Nov 2019 01:23:46 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=colorremedies-com.20150623.gappssmtp.com header.i=@colorremedies-com.20150623.gappssmtp.com header.b="Ehwo9jvl" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727138AbfK1BXp (ORCPT ); Wed, 27 Nov 2019 20:23:45 -0500 Received: from mail-wr1-f46.google.com ([209.85.221.46]:35512 "EHLO mail-wr1-f46.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727088AbfK1BXp (ORCPT ); Wed, 27 Nov 2019 20:23:45 -0500 Received: by mail-wr1-f46.google.com with SMTP id s5so29019012wrw.2 for ; Wed, 27 Nov 2019 17:23:44 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=colorremedies-com.20150623.gappssmtp.com; s=20150623; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=5+fcuwvMCRziJ/N4d2u+3J1tnJLlV385BHcsg8oKn1g=; b=Ehwo9jvlkMoP52/ejMOF35obku4QoEZE73e+e2T1DaUChlbkDH8Q1MkOvyZl1UUVIg M/wUo8dKRbn3f/1ySvF8Y17rCO8aQ6yXF2nKZMOy1KheL3I3LWwUDMLrZDC3HC8qoHIZ ZmikGvDQCJRGovCht6saBq+45q3NvmEnvGTTnJovF8Wzy2PsTnVcHcUmavclUvO9xHWT MaqBJmEz+tq30tOvPh6VPeqDg21g2kLX0pF0gPqnzNuuYnF/vMMHO2fpNS71Wgcf8seZ Kjh/aVJz94sUwwVzvEpSStLRqtfqkQrfo1a2eXIEb5HglQyiIJpVKWx1vO0Ch54WuCcF fWxg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=5+fcuwvMCRziJ/N4d2u+3J1tnJLlV385BHcsg8oKn1g=; b=Izm1GvsNiuogqO8T4DLa73yi6RQTBVMmHWXA0WvFu3Y+RV611qmdtnngTB6AOPK37X uO491jsVmXcj9YfwdZx+VgPkKQ1KTrl9/B+iM71v6VjIC7Sq0AiAg9ZOAWQHV3gX6pK3 BgNpREwqGu6/TsEj3+1mZsUFvX8OIwAPdp5ws52ajnIIn69TPkhYNGo8G6FfwixDsKrp miv4wutebwMIfdI7ynzdV6O37MuS3Hkj/r62Hl5/l3mymiDcQnSJDX1aaXV8+US7xVkS HteRojqdCL1mW7AodsSIhPWLI9DCwCtcRAIhVZm2s5YkNIS2gOz2sLSx7h7+PO0EBhgt kD4A== X-Gm-Message-State: APjAAAUoQ86yNWKpw97rxDfO+wFZe7C4QQOLQBHh/2PhMSBlTbBQ5glH 5DiLl8kGzjfvyDSs+OXbgIgANI2zCEoM1gt7yFK+vQ== X-Google-Smtp-Source: APXvYqykYKc83BfndJnSsRri6hzSO7WLhAvQWDJI0iYmA1ajTLLPRLhgjm1m6Zozn93zJ/sp7uyYi8HbCtZEKa4pTis= X-Received: by 2002:adf:da52:: with SMTP id r18mr45307845wrl.167.1574904223218; Wed, 27 Nov 2019 17:23:43 -0800 (PST) MIME-Version: 1.0 References: In-Reply-To: From: Chris Murphy Date: Wed, 27 Nov 2019 18:23:27 -0700 Message-ID: Subject: Re: bad sector / bad block support To: Christopher Staples Cc: Btrfs BTRFS Content-Type: text/plain; charset="UTF-8" Sender: linux-btrfs-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-btrfs@vger.kernel.org On Tue, Nov 26, 2019 at 8:30 PM Christopher Staples wrote: > > will their ever be a better way to handle bad sectors ? I keep > getting silent corruption from random bad sectors > scrubs keep passing with out showing any errors , but if I do a > ddrescue backup to a new drive I find the bad sectors Bad sectors manifest in two ways: the drive reports UNC on read or write, or Btrfs reports a checksum mismatch. If Btrfs isn't catching it, but the data is wrong, it's probably a memory problem that causes the corruption and subsequently a checksum computation based on that corruption which is why Btrfs thinks it's correct. > I like btrfs for the snapshot ability , but when it comes to keeping > data safe ext4 seems better ? at least it looks for bad sectors and > marks them , btrfs just seems to write and assumes its written .. That's the wrong way of looking at it. If there are a small number of bad physical sectors, upon write, the drive firmware will remap the LBA to a reserve sector. There's no appearance of bad sectors outside the drive at all, and no error reported. That's normal behavior. If the drive has a lot of bad sectors, eventually all the reserve sectors get used up, and now the drive has to report UNC on write - a write error. This is a device that's inevitably going to betray you with far worse problems and data loss, so papering over it with an external bad sector map isn't something anyone will recommend in a data integrity context. Replace the drive. -- Chris Murphy