From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-io0-f193.google.com ([209.85.223.193]:38313 "EHLO mail-io0-f193.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751895AbdHBNru (ORCPT ); Wed, 2 Aug 2017 09:47:50 -0400 Received: by mail-io0-f193.google.com with SMTP id o9so3729673iod.5 for ; Wed, 02 Aug 2017 06:47:50 -0700 (PDT) Subject: Re: RedHat 7.4 Release Notes: "Btrfs has been deprecated" - wut? To: Lutz Vieweg , linux-btrfs@vger.kernel.org References: <84806456-eed9-00b9-b3f6-99e46cefba33@swiftspirit.co.za> <1cfc817b-2f35-9ca5-9d6c-ab2c6ec53ba9@gmail.com> From: "Austin S. Hemmelgarn" Message-ID: <5b59dfbb-ea90-d44a-e745-22d6543a93a1@gmail.com> Date: Wed, 2 Aug 2017 09:47:46 -0400 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8; format=flowed Sender: linux-btrfs-owner@vger.kernel.org List-ID: On 2017-08-02 08:55, Lutz Vieweg wrote: > On 08/02/2017 01:25 PM, Austin S. Hemmelgarn wrote: >> And this is a worst-case result of the fact that most >> distros added BTRFS support long before it was ready. > > RedHat still advertises "Ceph", and given Ceph initially recommended > btrfs as > the filesystem to use for its nodes, it is interesting to read how clearly > they recommend against btrfs now: > > http://docs.ceph.com/docs/master/rados/configuration/filesystem-recommendations/ > >> We recommand against using btrfs due to the lack of a stable version >> to test against and frequent bugs in the ENOSPC handling. Yes, and the one thing they don't mention there is that Ceph is already doing most of the same things that BTRFS is, so you end up having performance issues due to duplicated work too. What they specifically call out though is first the reason that it should not be supported yet in RHEL, OEL, and many other distros (I'm explicitly leaving SLES/OpenSUSE off of that list, because while I disagree with their choices of default behavior WRT BTRFS, they are actively involved in it's development, unlike most of the other distros that 'support' it), and then second one of the biggest issues for regular usage. > > German IT magazine "Golem" speculates that RedHat's decision > is influenced by its recent acquisition of Permabit. > > But I don't really see how XFS or Permabit tackle the problem > that if you need to create consistent backups of file systems while they > are > in use, block-device level snapshots damage the write performance > big time. When you're talking about data safety though, most people are willing to sacrifice write performance in favor of significantly lowering perceived risk. The misguided early support of BTRFS without sufficient explanation of exactly how 'in-development' it is by many distros means that there are a lot of stories of issues and failures with BTRFS than ones of success (partly also because the filesystem is one of those things that people tend to complain about if it breaks, and not praise all that much if it works), and as a result, the general perception outside of people who use it actively is that it's pretty risky to use (which is absolutely accurate if you don't do routine maintenance on it). > > (That backup topic is the one reason we use btrfs for a lot of > /home/ directories.) > > I understand that XFS is expected to get some COW-features in the future > as well - but it remains to be seen what performance and robustness > implications that will have on XFS. I believe basic reflink functionality is already upstream, and I wasn't aware of any other specific development for XFS.