From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-ot0-f181.google.com ([74.125.82.181]:40790 "EHLO mail-ot0-f181.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750829AbeAMWJL (ORCPT ); Sat, 13 Jan 2018 17:09:11 -0500 Received: by mail-ot0-f181.google.com with SMTP id d10so7878980oti.7 for ; Sat, 13 Jan 2018 14:09:10 -0800 (PST) MIME-Version: 1.0 In-Reply-To: References: From: Chris Murphy Date: Sat, 13 Jan 2018 15:09:09 -0700 Message-ID: Subject: Re: Recommendations for balancing as part of regular maintenance? To: "Austin S. Hemmelgarn" Cc: Btrfs BTRFS Content-Type: text/plain; charset="UTF-8" Sender: linux-btrfs-owner@vger.kernel.org List-ID: On Fri, Jan 12, 2018 at 11:24 AM, Austin S. Hemmelgarn wrote: > To that end, I propose the following text for the FAQ: > > Q: Do I need to run a balance regularly? > > A: While not strictly necessary for normal operations, running a filtered > balance regularly can help prevent your filesystem from ending up with > ENOSPC issues. The following command run daily on each BTRFS volume should > be more than sufficient for most users: > > `btrfs balance start -dusage=25 -dlimit=2..10 -musage=25 -mlimit=2..10` Daily? Seems excessive. I've got multiple Btrfs file systems that I haven't balanced, full or partial, in a year. And I have no problems. One is a laptop which accumulates snapshots until roughly 25% free space remains and then most of the snapshots are deleted, except the most recent few, all at one time. I'm not experiencing any problems so far. The other is a NAS and it's multiple copies, with maybe 100-200 snapshots. One backup volume is 99% full, there's no more unallocated free space, I delete snapshots only to make room for btrfs send receive to keep pushing the most recent snapshot from the main volume to the backup. Again no problems. I really think suggestions this broad are just going to paper over bugs or design flaws, we won't see as many bug reports and then real problems won't get fixed. I also thing the time based method is too subjective. What about the layout means a balance is needed? And if it's really a suggestion, why isn't there a chron or systemd unit that just does this for the user, in btrfs-progs, working and enabled by default? I really do not like all this hand holding of Btrfs, it's not going to make it better. > A full, unfiltered balance (one without any options passed in) is completely > unnecessary for normal usage of a filesystem. That's good advice. -- Chris Murphy