From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-yk0-f179.google.com ([209.85.160.179]:34270 "EHLO mail-yk0-f179.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750915AbbFQAOG (ORCPT ); Tue, 16 Jun 2015 20:14:06 -0400 Received: by ykfl8 with SMTP id l8so27303633ykf.1 for ; Tue, 16 Jun 2015 17:14:05 -0700 (PDT) MIME-Version: 1.0 In-Reply-To: References: <1434456557.89597618@apps.rackspace.com> <20150616122545.GI9850@carfax.org.uk> <61CBE6C4-0D06-4F16-B522-4DBB756FBC31@up4.com> Date: Tue, 16 Jun 2015 18:14:05 -0600 Message-ID: Subject: Re: RAID10 Balancing Request for Comments and Advices From: Chris Murphy To: Btrfs BTRFS Content-Type: text/plain; charset=UTF-8 Sender: linux-btrfs-owner@vger.kernel.org List-ID: On Tue, Jun 16, 2015 at 5:58 PM, Duncan <1i5t5.duncan@cox.net> wrote: > On a current kernel unlike older ones, btrfs actually automates entirely > empty chunk reclaim, so this problem doesn't occur anything close to near > as often as it used to. However, it's still possible to have mostly but > not entirely empty chunks that btrfs won't automatically reclaim. A > balance can be used to rewrite and combine these mostly empty chunks, > reclaiming the space saved. This is what Hugo was recommending. Yes, as little as a -dusage=5 (data chunks that are 5% or less full) can clear the problem and is very fast, seconds. Possibly a bit longer, many seconds o single digit minutes is -dusage=15. I haven't done a full balance in forever. -- Chris Murphy