From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 38186C0032E for ; Wed, 25 Oct 2023 21:16:04 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229704AbjJYVQE convert rfc822-to-8bit (ORCPT ); Wed, 25 Oct 2023 17:16:04 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:60206 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229441AbjJYVQD (ORCPT ); Wed, 25 Oct 2023 17:16:03 -0400 Received: from shin.romanrm.net (shin.romanrm.net [146.185.199.61]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 3B26E132 for ; Wed, 25 Oct 2023 14:15:59 -0700 (PDT) Received: from nvm (nvm2.home.romanrm.net [IPv6:fd39::4a:3cff:fe57:d6b5]) by shin.romanrm.net (Postfix) with SMTP id 3261A3F37B; Wed, 25 Oct 2023 21:15:54 +0000 (UTC) Date: Thu, 26 Oct 2023 02:15:51 +0500 From: Roman Mamedov To: Remi Gauvin Cc: "linux-btrfs@vger.kernel.org" Subject: Re: Balance on 5-disk RAID1 put all data on 2 disks, leaving the rest empty Message-ID: <20231026021551.55802873@nvm> In-Reply-To: <16acffd1-9704-9681-c2d4-4f5b8280ade0@georgianit.com> References: <16acffd1-9704-9681-c2d4-4f5b8280ade0@georgianit.com> X-Mailer: Claws Mail 3.11.1 (GTK+ 2.24.31; x86_64-pc-linux-gnu) MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8BIT Precedence: bulk List-ID: X-Mailing-List: linux-btrfs@vger.kernel.org On Wed, 25 Oct 2023 17:08:08 -0400 Remi Gauvin wrote: > On 2023-10-25 4:29 p.m., Peter Wedder wrote: > > Hello, > > > > I had a RAID1 array on top of 4x4TB drives. Recently I removed one 4TB drive and added two 16TB drives to it. After running a full, unfiltered balance on the array, I am left in a situation where all the 4TB drives are completely empty, and all the data and metadata is on the 16TB drives. Is this normal? I was expecting to have at least some data on the smaller drives. > > > > Yes, this is normal.  The BTRFS allocates space in drives with the the > most available free space.  The idea is to balance the 'unallocated' > space on each drive, so they can be filled evenly.  The 4TB drives will > be used when the 16TB dives have less than 4TB unallocated. Interesting question and resolution. I'd be surprised by that as well. Now, a great chance to "btrfs dev delete" all three remaining 4TB drives and unplug them for the time being, to save on noise, heat and power consumption! -- With respect, Roman