From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from plane.gmane.org ([80.91.229.3]:39665 "EHLO plane.gmane.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1422708AbbEOPgU (ORCPT ); Fri, 15 May 2015 11:36:20 -0400 Received: from list by plane.gmane.org with local (Exim 4.69) (envelope-from ) id 1YtHer-0000QQ-K0 for linux-btrfs@vger.kernel.org; Fri, 15 May 2015 17:36:17 +0200 Received: from c-73-47-108-123.hsd1.ma.comcast.net ([73.47.108.123]) by main.gmane.org with esmtp (Gmexim 0.1 (Debian)) id 1AlnuQ-0007hv-00 for ; Fri, 15 May 2015 17:36:17 +0200 Received: from cdysthe by c-73-47-108-123.hsd1.ma.comcast.net with local (Gmexim 0.1 (Debian)) id 1AlnuQ-0007hv-00 for ; Fri, 15 May 2015 17:36:17 +0200 To: linux-btrfs@vger.kernel.org From: Christian Subject: Re: Mysterious device (id 0). Date: Fri, 15 May 2015 11:36:10 -0400 Message-ID: References: <5555D78D.5040909@gmail.com> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8; format=flowed In-Reply-To: <5555D78D.5040909@gmail.com> Sender: linux-btrfs-owner@vger.kernel.org List-ID: On 05/15/2015 07:25 AM, Austin S Hemmelgarn wrote: > On 2015-05-14 20:09, Christian wrote: >> Hi, >> >> My laptop has a small ext4 /boot partition /dev/sda1 and a large btrfs >> partition containing / and /home as a sub volume /dev/sda3 >> >> When I run scrub on /dev/sda3 and check status with sudo btrfs scrub >> status -d /dev/sda3 I get: >> >> scrub status for 3d52dc93-c89f-453f-965d-8601d11e7710 >> scrub device /dev/sda3 (id 1) history >> scrub started at Thu May 14 19:54:02 2015 and finished after 235 >> seconds >> total bytes scrubbed: 111.03GiB with 0 errors >> scrub device (id 0) history >> scrub started at Thu May 14 19:54:02 2015 and was aborted after 0 >> seconds >> total bytes scrubbed: 0.00B with 0 errors >> >> As device (id 0) is indicated, but I have no idea what it is. >> >> When I run scrub with a script (cron) the same device (id 0) shows up in >> a warning: >> >> /etc/cron.daily/btrfs-scrub: >> WARNING: device 0 not present >> scrub device /dev/sda3 (id 1) done >> scrub started at Sat May 2 08:03:46 2015 and finished after 241 >> seconds >> total bytes scrubbed: 109.06GiB with 0 errors >> scrub device (id 0) canceled >> scrub started at Sat May 2 08:03:46 2015 and was aborted after 0 >> seconds >> total bytes scrubbed: 0.00B with 0 errors >> >> What is this device (id 0) which never gets scrubbed but always shows up? >> >> I'm running Ubuntu 15.04 with the 3.19.0-16-generic kernel. >> > Have you ever run 'btrfs replace' to replace a device in the filesystem? > I know that new device in a replace operation get's tagged as device > id 0 until the replace operation completes (at which point it gets the > devid of the device it replaced). Personally, this is the only case > that I know of that devid 0 is actually used in the code. Thinking > further though, it might also be an off-by-one error somewhere, although > I have no idea where. > > No, I have never run 'btrfs replace'. This problem was discussed in a previous thread covering the script I am using for daily scrub. The author had the same problem, but for him it simply went away. Not for me though. The thread was "Re: 3.19.3: check tree block failed + WARNING: device 0 not present on scrub". I have had some problems with btrfs in the past so I am very ware of any error message! I can't live without the snapshots anymore though :) -- //Christian