From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from atl4mhob12.myregisteredsite.com ([209.17.115.50]:54450 "EHLO atl4mhob12.myregisteredsite.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755423Ab3FCCLG (ORCPT ); Sun, 2 Jun 2013 22:11:06 -0400 Received: from mailpod1.hostingplatform.com ([10.30.71.113]) by atl4mhob12.myregisteredsite.com (8.14.4/8.14.4) with ESMTP id r532B3Sk006476 for ; Sun, 2 Jun 2013 22:11:03 -0400 Message-ID: <51ABFB3E.6050408@chinilu.com> Date: Sun, 02 Jun 2013 19:11:10 -0700 From: George Mitchell Reply-To: george@chinilu.com MIME-Version: 1.0 To: bo.li.liu@oracle.com CC: linux-btrfs@vger.kernel.org Subject: Re: Is there a way to flag specific directories "nodatacow"? References: <51AB5974.3080803@chinilu.com> <20130603012848.GA26016@liubo.jp.oracle.com> In-Reply-To: <20130603012848.GA26016@liubo.jp.oracle.com> Content-Type: text/plain; charset=UTF-8; format=flowed Sender: linux-btrfs-owner@vger.kernel.org List-ID: On 06/02/2013 06:28 PM, Liu Bo wrote: > On Sun, Jun 02, 2013 at 07:40:52AM -0700, George Mitchell wrote: >> I am seeing massive journal corruptions that seem to be unique to >> btrfs and I am suspecting that cow might be causing them. My >> bandaid fix for this will be to mark the /var filesystem "nodatacow" >> at boot. But I am wondering if their is any way to flag a >> particular directory as "nodatacow" outside of the mount process. I >> would like to be able to mark /var/log/journal as "nodatacow" for >> example, without having to declare it a subvolume and mount it >> separately. > Hi George, > > We actually have per-file/directory nodatacow :) > > But please note if you set nodatacow on the particular directory, only > new-created or zero-size files in the directory can follow the nocow rule. > > 'chattr' in the latest e2fsprogs can fit your requirements, > # chattr +C /var/log/journal > > Also, what kind of massive journal corruptions? Does it look like a > btrfs specific bug? > > thanks, > liubo > > Thanks Liu, That helps a lot! I am very familiar with chattr/lsattr from my ext3 days, but didn't know where to look for btrfs options. From what you are telling me the nodatacow option is identical to nodatacow option for ext3. Do the other ext3 options work for btrfs also? As for as the corruption issue, I actually don't know whether the corruptions are real or whether they are being caused by the way the `journalctl --verify` command is interfacing with the filesystem. My suspicion is that metadata fragmentation *might* be somehow messing with the `journalctl --verify` since I can use simply `journalctl` and all the data flows out without error. I just cleaned out the /var/log/journal directory and started fresh and in no time I am seeing corruptions according to `journalctl --verify`. Here is what the output looks like: ============================================================================== [root@localhost aide]# journalctl --verify Invalid object contents at 130624░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░ 0% File corruption detected at /var/log/journal/8846d97f611b49aa9f3d48eeac6a81f2/system@e1447322cf904d028439c2d3f17d032e-0000000000000628-0004de2c1807989c.journal:130624 (of 131072, 99%). FAIL: /var/log/journal/8846d97f611b49aa9f3d48eeac6a81f2/system@e1447322cf904d028439c2d3f17d032e-0000000000000628-0004de2c1807989c.journal (Bad message) PASS: /var/log/journal/8846d97f611b49aa9f3d48eeac6a81f2/user-501@e1447322cf904d028439c2d3f17d032e-000000000000065a-0004de2c18d6d96d.journal Invalid object contents at 125264░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░ 0% File corruption detected at /var/log/journal/8846d97f611b49aa9f3d48eeac6a81f2/system@e1447322cf904d028439c2d3f17d032e-000000000000069a-0004de2c5e323847.journal:125264 (of 131072, 95%). FAIL: /var/log/journal/8846d97f611b49aa9f3d48eeac6a81f2/system@e1447322cf904d028439c2d3f17d032e-000000000000069a-0004de2c5e323847.journal (Bad message) PASS: /var/log/journal/8846d97f611b49aa9f3d48eeac6a81f2/user-501@e1447322cf904d028439c2d3f17d032e-00000000000006a8-0004de2c73b5f19d.journal Invalid object contents at 128408░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░ 0% File corruption detected at /var/log/journal/8846d97f611b49aa9f3d48eeac6a81f2/system@e1447322cf904d028439c2d3f17d032e-0000000000000709-0004de2cedab583c.journal:128408 (of 131072, 97%). FAIL: /var/log/journal/8846d97f611b49aa9f3d48eeac6a81f2/system@e1447322cf904d028439c2d3f17d032e-0000000000000709-0004de2cedab583c.journal (Bad message) Invalid object contents at 126736░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░ 0% File corruption detected at /var/log/journal/8846d97f611b49aa9f3d48eeac6a81f2/system@e1447322cf904d028439c2d3f17d032e-000000000000077f-0004de2d20abe261.journal:126736 (of 131072, 96%). FAIL: /var/log/journal/8846d97f611b49aa9f3d48eeac6a81f2/system@e1447322cf904d028439c2d3f17d032e-000000000000077f-0004de2d20abe261.journal (Bad message) Invalid object contents at 129600░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░ 0% File corruption detected at /var/log/journal/8846d97f611b49aa9f3d48eeac6a81f2/system@e1447322cf904d028439c2d3f17d032e-00000000000007ec-0004de2d7c50c186.journal:129600 (of 131072, 98%). FAIL: /var/log/journal/8846d97f611b49aa9f3d48eeac6a81f2/system@e1447322cf904d028439c2d3f17d032e-00000000000007ec-0004de2d7c50c186.journal (Bad message) PASS: /var/log/journal/8846d97f611b49aa9f3d48eeac6a81f2/user-501@e1447322cf904d028439c2d3f17d032e-00000000000007f1-0004de2d87392b08.journal Invalid object contents at 129256░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░ 0% File corruption detected at /var/log/journal/8846d97f611b49aa9f3d48eeac6a81f2/system@e1447322cf904d028439c2d3f17d032e-0000000000000862-0004de2e9a6decf4.journal:129256 (of 131072, 98%). FAIL: /var/log/journal/8846d97f611b49aa9f3d48eeac6a81f2/system@e1447322cf904d028439c2d3f17d032e-0000000000000862-0004de2e9a6decf4.journal (Bad message) PASS: /var/log/journal/8846d97f611b49aa9f3d48eeac6a81f2/user-501@e1447322cf904d028439c2d3f17d032e-000000000000087d-0004de2eaee97998.journal Invalid object contents at 126032░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░ 0% File corruption detected at /var/log/journal/8846d97f611b49aa9f3d48eeac6a81f2/system@e1447322cf904d028439c2d3f17d032e-00000000000008de-0004de2fb88c29cb.journal:126032 (of 131072, 96%). FAIL: /var/log/journal/8846d97f611b49aa9f3d48eeac6a81f2/system@e1447322cf904d028439c2d3f17d032e-00000000000008de-0004de2fb88c29cb.journal (Bad message) PASS: /var/log/journal/8846d97f611b49aa9f3d48eeac6a81f2/user-501@e1447322cf904d028439c2d3f17d032e-0000000000000947-0004de30cc6f8833.journal Invalid object contents at 130952░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░ 0% File corruption detected at /var/log/journal/8846d97f611b49aa9f3d48eeac6a81f2/system@e1447322cf904d028439c2d3f17d032e-0000000000000957-0004de30d6aad93f.journal:130952 (of 131072, 99%). FAIL: /var/log/journal/8846d97f611b49aa9f3d48eeac6a81f2/system@e1447322cf904d028439c2d3f17d032e-0000000000000957-0004de30d6aad93f.journal (Bad message) PASS: /var/log/journal/8846d97f611b49aa9f3d48eeac6a81f2/user-501@e1447322cf904d028439c2d3f17d032e-000000000000098b-0004de31213bbbae.journal Invalid object contents at 124168░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░ 0% File corruption detected at /var/log/journal/8846d97f611b49aa9f3d48eeac6a81f2/system@e1447322cf904d028439c2d3f17d032e-00000000000009d1-0004de31f4c7533d.journal:124168 (of 131072, 94%). FAIL: /var/log/journal/8846d97f611b49aa9f3d48eeac6a81f2/system@e1447322cf904d028439c2d3f17d032e-00000000000009d1-0004de31f4c7533d.journal (Bad message) Invalid object contents at 130784░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░ 0% File corruption detected at /var/log/journal/8846d97f611b49aa9f3d48eeac6a81f2/system@e1447322cf904d028439c2d3f17d032e-0000000000000a47-0004de3312e5e75d.journal:130784 (of 131072, 99%). FAIL: /var/log/journal/8846d97f611b49aa9f3d48eeac6a81f2/system@e1447322cf904d028439c2d3f17d032e-0000000000000a47-0004de3312e5e75d.journal (Bad message) PASS: /var/log/journal/8846d97f611b49aa9f3d48eeac6a81f2/user-501@e1447322cf904d028439c2d3f17d032e-0000000000000a8d-0004de33b65f55f2.journal Invalid object contents at 129744░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░ 0% File corruption detected at /var/log/journal/8846d97f611b49aa9f3d48eeac6a81f2/system@e1447322cf904d028439c2d3f17d032e-0000000000000abb-0004de33e97b96d8.journal:129744 (of 131072, 98%). FAIL: /var/log/journal/8846d97f611b49aa9f3d48eeac6a81f2/system@e1447322cf904d028439c2d3f17d032e-0000000000000abb-0004de33e97b96d8.journal (Bad message) PASS: /var/log/journal/8846d97f611b49aa9f3d48eeac6a81f2/user-501@e1447322cf904d028439c2d3f17d032e-0000000000000ad1-0004de341fd95f50.journal Invalid object contents at 129864░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░ 0% File corruption detected at /var/log/journal/8846d97f611b49aa9f3d48eeac6a81f2/system@e1447322cf904d028439c2d3f17d032e-0000000000000b37-0004de34e40af053.journal:129864 (of 131072, 99%). FAIL: /var/log/journal/8846d97f611b49aa9f3d48eeac6a81f2/system@e1447322cf904d028439c2d3f17d032e-0000000000000b37-0004de34e40af053.journal (Bad message) PASS: /var/log/journal/8846d97f611b49aa9f3d48eeac6a81f2/system.journal ============================================================================== So I want to try forcing "nodatacow" on this directory and see what happens. If that doesn't work, I suppose the next step will be to place this one directory on an ext4 filesystem and mount it externally to the btrfs /var/log. What I do know is that I have a parallel maintenance system on the same hardware using ext4 and it has never had a problem like this. I have also had a boot problem from the beginning and that seems like it got fixed by doing rigorous defragmentation on the btrfs root filesystem. So I really don't know at this point what is causing this problem, but I am determined to do my best to find out. The system I am having the problem with has been running Mageia 3 100% on btrfs RAID 1 migrated from Mageia 2 100% on 3ware hardware RAID 1. Making this transition has been a quite an experience, but the system is up and running fine. This is my day to day production system and since btrfs is where it is right now, this system is rigorously backed up every three hours to a JFS formatted drive and daily to a 4TB btrfs formatted drive. The system is also on UPS, but has actually hard crashed multiple times early on without any resulting data corruption. But only by using btrfs on a production system can I shag out all of these peripheral issues. So thanks so much for the tip, it will get me one step further along in sorting this out. Sincerely, George