From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-oi0-f47.google.com ([209.85.218.47]:52423 "EHLO mail-oi0-f47.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751915AbdKHEuW (ORCPT ); Tue, 7 Nov 2017 23:50:22 -0500 Received: by mail-oi0-f47.google.com with SMTP id r128so1104787oig.9 for ; Tue, 07 Nov 2017 20:50:22 -0800 (PST) MIME-Version: 1.0 In-Reply-To: <2164b4b2-1447-3670-73ae-465404754b87@gmail.com> References: <9871a669-141b-ac64-9da6-9050bcad7640@cn.fujitsu.com> <2164b4b2-1447-3670-73ae-465404754b87@gmail.com> From: Chris Murphy Date: Tue, 7 Nov 2017 21:50:20 -0700 Message-ID: Subject: Re: Problem with file system To: "Austin S. Hemmelgarn" Cc: Dave , Linux fs Btrfs , Chris Murphy Content-Type: text/plain; charset="UTF-8" Sender: linux-btrfs-owner@vger.kernel.org List-ID: On Tue, Nov 7, 2017 at 6:02 AM, Austin S. Hemmelgarn wrote: > * Optional automatic correction of errors detected during normal usage. > Right now, you have to run a scrub to correct errors. Such a design makes > sense with MD and LVM, where you don't know which copy is correct, but BTRFS > does know which copy is correct (or how to rebuild the correct data), and it > therefore makes sense to have an option to automatically rebuild data that > is detected to be incorrect. ? It definitely does fix ups during normal operations. During reads, if there's a UNC or there's corruption detected, Btrfs gets the good copy, and does a (I think it's an overwrite, not COW) fixup. Fixups don't just happen with scrubbing. Even raid56 supports these kinds of passive fixups back to disk. -- Chris Murphy