From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-io0-f173.google.com ([209.85.223.173]:45276 "EHLO mail-io0-f173.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S934187AbeAHPzz (ORCPT ); Mon, 8 Jan 2018 10:55:55 -0500 Received: by mail-io0-f173.google.com with SMTP id e20so14557500iof.12 for ; Mon, 08 Jan 2018 07:55:54 -0800 (PST) Received: from [191.9.212.201] (rrcs-70-62-41-24.central.biz.rr.com. [70.62.41.24]) by smtp.gmail.com with ESMTPSA id c17sm7288584iob.66.2018.01.08.07.55.52 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Mon, 08 Jan 2018 07:55:52 -0800 (PST) To: Btrfs BTRFS From: "Austin S. Hemmelgarn" Subject: Recommendations for balancing as part of regular maintenance? Message-ID: Date: Mon, 8 Jan 2018 10:55:51 -0500 MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8; format=flowed Sender: linux-btrfs-owner@vger.kernel.org List-ID: So, for a while now I've been recommending small filtered balances to people as part of regular maintenance for BTRFS filesystems under the logic that it does help in some cases and can't really hurt (and if done right, is really inexpensive in terms of resources). This ended up integrated partially in the info text next to the BTRFS charts on netdata's dashboard, and someone has now pointed out (correctly I might add) that this is at odds with the BTRFS FAQ entry on balances. For reference, here's the bit about it in netdata: You can keep your volume healthy by running the `btrfs balance` command on it regularly (check `man btrfs-balance` for more info). And here's the FAQ entry: Q: Do I need to run a balance regularly? A: In general usage, no. A full unfiltered balance typically takes a long time, and will rewrite huge amounts of data unnecessarily. You may wish to run a balance on metadata only (see Balance_Filters) if you find you have very large amounts of metadata space allocated but unused, but this should be a last resort. I've commented in the issue in netdata's issue tracker that I feel that the FAQ entry could be better worded (strictly speaking, you don't _need_ to run balances regularly, but it's usually a good idea). Looking at both though, I think they could probably both be improved, but I would like to get some input here on what people actually think the best current practices are regarding this (and ideally why they feel that way) before I go and change anything. So, on that note, how does anybody else out there feel about this? Is balancing regularly with filters restricting things to small numbers of mostly empty chunks a good thing for regular maintenance or not?