From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-it0-f43.google.com ([209.85.214.43]:38034 "EHLO mail-it0-f43.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750713AbcIAUzx (ORCPT ); Thu, 1 Sep 2016 16:55:53 -0400 Received: by mail-it0-f43.google.com with SMTP id c198so3105913ith.1 for ; Thu, 01 Sep 2016 13:55:52 -0700 (PDT) Subject: Re: BTRFS constantly reports "No space left on device" even with a huge unallocated space To: Ronan Arraes Jardim Chagas , Chris Murphy , Jeff Mahoney References: <1471023419.16857.9.camel@gmail.com> <57C426AB.3020607@cn.fujitsu.com> <1472485953.3290.0.camel@gmail.com> <57C4EB85.7030000@cn.fujitsu.com> <1472561404.3179.3.camel@gmail.com> <1472676550.8145.1.camel@gmail.com> <52290114-3b37-2de5-9c9f-ceda6dff955b@suse.com> <1472734635.3137.4.camel@gmail.com> <0778dff0-cb43-d279-adb2-0e314b61110d@gmail.com> <1472747695.3137.7.camel@gmail.com> Cc: Wang Xiaoguang , Btrfs BTRFS , Qu Wenruo From: "Austin S. Hemmelgarn" Message-ID: Date: Thu, 1 Sep 2016 13:04:56 -0400 MIME-Version: 1.0 In-Reply-To: <1472747695.3137.7.camel@gmail.com> Content-Type: text/plain; charset=utf-8; format=flowed Sender: linux-btrfs-owner@vger.kernel.org List-ID: On 2016-09-01 12:34, Ronan Arraes Jardim Chagas wrote: > Em Qui, 2016-09-01 às 09:21 -0400, Austin S. Hemmelgarn escreveu: >> Yes, you can just run `btrfs quota disable /` and it should >> work. This >> ironically reiterates that one of the bigger problems with BTRFS is >> that >> distros are enabling unstable and known broken features by default >> on >> install. I was pretty much dumbfounded when I first learned that >> OpenSUSE is enabling BTRFS qgroups by default since they are known >> to >> not work reliably and cause all kinds of issues. > > Thanks Austin! I executed the command and now I get: > > btrfs qgroup show / > ERROR: can't perform the search - No such file or directory > ERROR: can't list qgroups: No such file or directory > > as expected. Now I will wait for +- 1 week to see if the problem will > occur and, if not, I will send an e-mail to openSUSE factory mailing > list to start a discussion if it is better to not enable qgroups by > default. I have a feeling that you'll probably have no issues. As far as having qgroups enabled by default, I think the reasoning is to emulate having separate filesystems with their own space limits. I can entirely understand this use case, and TBH it's about the only use case I'd consider quota groups for (per-user subvolumes for home directories are great, but there are numerous perfectly legitimate reasons to have very large amounts of data in your home directory for very short periods of time, so I wouldn't personally use qgroups there). The problem arises from the fact that it doesn't _look_ like separate filesystems (single entry in df, all the mounts point at the same device, etc), and the standard of overloading ENOSPC to mean you've hit your quota leads to lots of confusion in this particular case (especially considering the free space issues that BTRFS is known to have from time to time).