From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-wm0-f46.google.com ([74.125.82.46]:36177 "EHLO mail-wm0-f46.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751631AbcAEQYe (ORCPT ); Tue, 5 Jan 2016 11:24:34 -0500 Received: by mail-wm0-f46.google.com with SMTP id l65so29051881wmf.1 for ; Tue, 05 Jan 2016 08:24:33 -0800 (PST) Received: from [192.168.2.69] (23.115.135.37.dynamic.jazztel.es. [37.135.115.23]) by smtp.gmail.com with ESMTPSA id kb5sm91434172wjc.20.2016.01.05.08.24.31 for (version=TLSv1/SSLv3 cipher=OTHER); Tue, 05 Jan 2016 08:24:32 -0800 (PST) To: Btrfs BTRFS From: Psalle Subject: raid1 vs raid5 Message-ID: <568BEE3F.4060402@gmail.com> Date: Tue, 5 Jan 2016 17:24:31 +0100 MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8; format=flowed Sender: linux-btrfs-owner@vger.kernel.org List-ID: Hello all and excuse me if this is a silly question. I looked around in the wiki and list archives but couldn't find any in-depth discussion about this: I just realized that, since raid1 in btrfs is special (meaning only two copies in different devices), the effect in terms of resilience achieved with raid1 and raid5 are the same: you can lose one drive and not lose data. So!, presuming that raid5 were at the same level of maturity, what would be the pros/cons of each mode? As a corollary, I guess that if raid1 is considered a good compromise, then functional equivalents to raid6 and beyond could simply be implemented as "storing n copies in different devices", dropping any complex parity computations and making this mode entirely generic. Since this seems pretty obvious, I'd welcome your insights on what are the things I'm missing, since it doesn't exist (and it isn't planned to be this way, AFAIK). I can foresee consistency difficulties, but that seems hardly insurmountable if its being done for raid1? Thanks in advance, Psalle.