From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from magic.merlins.org ([209.81.13.136]:47506 "EHLO mail1.merlins.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753076AbeGCVkr (ORCPT ); Tue, 3 Jul 2018 17:40:47 -0400 Date: Tue, 3 Jul 2018 14:40:41 -0700 From: Marc MERLIN To: Chris Murphy Cc: Su Yue , Qu Wenruo , Btrfs BTRFS Subject: Re: So, does btrfs check lowmem take days? weeks? Message-ID: <20180703214041.4cywam4m4ivipgau@merlins.org> References: <20180701232202.vehg7amgyvz3hpxc@merlins.org> <5a603d3d-620b-6cb3-106c-9d38e3ca6d02@cn.fujitsu.com> <20180702032259.GD5567@merlins.org> <9fbd4b39-fa75-4c30-eea8-e789fd3e4dd5@cn.fujitsu.com> <20180702140527.wfbq5jenm67fvvjg@merlins.org> <3728d88c-29c1-332b-b698-31a0b3d36e2b@gmx.com> <20180703042241.GI5567@merlins.org> <704a82af-7cef-7981-b620-0e63a35620b3@cn.fujitsu.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii In-Reply-To: Sender: linux-btrfs-owner@vger.kernel.org List-ID: On Tue, Jul 03, 2018 at 03:34:45PM -0600, Chris Murphy wrote: > On Tue, Jul 3, 2018 at 2:34 AM, Su Yue wrote: > > > Yes, extent tree is the hardest part for lowmem mode. I'm quite > > confident the tool can deal well with file trees(which records metadata > > about file and directory name, relationships). > > As for extent tree, I have few confidence due to its complexity. > > I have to ask again if there's some metadata integrity mask opion Marc > should use to try to catch the corruption cause in the first place? > > His use case really can't afford either mode of btrfs check. And also > check is only backward looking, it doesn't show what was happening at > the time. And for big file systems, check rapidly doesn't scale at all > anyway. > > And now he's modifying his layout to avoid the problem from happening > again which makes it less likely to catch the cause, and get it fixed. > I think if he's willing to build a kernel with integrity checker > enabled, it should be considered but only if it's likely to reveal why > the problem is happening, even if it can't repair the problem once > it's happened. He's already in that situation so masked integrity > checking is no worse, at least it gives a chance to improve Btrfs > rather than it being a mystery how it got corrupt. Yeah, I'm fine waiting a few more ays with this down and gather data if that helps. But due to the size, a full btrfs image may be a bit larger than we want, not counting some confidential data in some filenames. Marc -- "A mouse is a device used to point at the xterm you want to type in" - A.S.R. Microsoft is to operating systems .... .... what McDonalds is to gourmet cooking Home page: http://marc.merlins.org/ | PGP 7F55D5F27AAF9D08