From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-it0-f49.google.com ([209.85.214.49]:37187 "EHLO mail-it0-f49.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753425AbcJKRGg (ORCPT ); Tue, 11 Oct 2016 13:06:36 -0400 Received: by mail-it0-f49.google.com with SMTP id z65so25603099itc.0 for ; Tue, 11 Oct 2016 10:06:36 -0700 (PDT) Subject: Re: RAID system with adaption to changed number of disks To: Philip Louis Moetteli , "linux-btrfs@vger.kernel.org" References: From: "Austin S. Hemmelgarn" Message-ID: <6e905424-928c-6e9f-a660-064edd12c37c@gmail.com> Date: Tue, 11 Oct 2016 12:37:18 -0400 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8; format=flowed Sender: linux-btrfs-owner@vger.kernel.org List-ID: On 2016-10-11 11:14, Philip Louis Moetteli wrote: > Hello, > > > I have to build a RAID 6 with the following 3 requirements: > > • Use different kinds of disks with different sizes. > • When a disk fails and there's enough space, the RAID should be able to reconstruct itself out of the degraded state. Meaning, if I have e. g. a RAID with 8 disks and 1 fails, I should be able to chose to transform this in a non-degraded (!) RAID with 7 disks. > • Also the other way round: If I add a disk of what size ever, it should redistribute the data, so that it becomes a RAID with 9 disks. > > I don’t care, if I have to do it manually. > I don’t care so much about speed either. > > Is BTrFS capable of doing that? In theory yes. In practice, BTRFS RAID5/6 mode should not be used in production due to a number of known serious issues relating to rebuilding and reshaping arrays.