From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from capsec.org ([46.4.123.73]:37712 "EHLO mail.capsec.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753300AbdBDBrT (ORCPT ); Fri, 3 Feb 2017 20:47:19 -0500 Mime-Version: 1.0 Date: Sat, 04 Feb 2017 01:47:46 +0000 Content-Type: text/plain; charset="utf-8" Message-ID: From: "Jorg Bornschein" Subject: Re: Very slow balance / btrfs-transaction To: "Goldwyn Rodrigues" , linux-btrfs@vger.kernel.org In-Reply-To: References: <507c32d4-929c-b691-6196-103c8cb9addb@suse.com> <80d3e5ce55ddc7e454cce96e67e2ea64@88cbed2449cf> <8999d95dac21ea8e2908c5012e50c59b@88cbed2449cf> Sender: linux-btrfs-owner@vger.kernel.org List-ID: February 4, 2017 1:07 AM, "Goldwyn Rodrigues" wrote: > On 02/03/2017 06:30 PM, Jorg Bornschein wrote: > >> February 3, 2017 11:26 PM, "Goldwyn Rodrigues" wrote: >> >> Hi, >> >> I'm currently running a balance (without any filters) on a 4 drives raid1 filesystem. The array >> contains 3 3TB drives and one 6TB drive; I'm running the rebalance because the 6TB drive recently >> replaced a 2TB drive. >> >> I know that balance is not supposed to be a fast operation, but this one is now running for ~6 days >> and it managed to balance ~18% (754 out of about 4250 chunks balanced (755 considered), 82% left) >> -- so I expect it to take another ~4 weeks. >> >> That seems excessively slow for ~8TiB of data. >> >> Is this expected behavior? In case it's not: Is there anything I can do to help debug it? >>> Do you have quotas enabled? >> >> I might have activated it when playing with "snapper" -- I remember using some quota command >> without knowing what it does. >> >> How can I check its active? Shall I just disable it wit "btrfs quota disable"? > > To check your quota limits: > # btrfs qgroup show > > To disable > # btrfs quota disable > > Yes, please check if disabling quotas makes a difference in execution > time of btrfs balance. Quata support was indeed active -- and it warned me that the qroup data was inconsistent. Disabling quotas had an immediate impact on balance throughput -- it's *much* faster now! >>From a quick glance at iostat I would guess it's at least a factor 100 faster. Should quota support generally be disabled during balances? Or did I somehow push my fs into a weired state where it triggered a slow-path? Thanks! j