From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mo4-p00-ob.smtp.rzone.de ([81.169.146.221]:57175 "EHLO mo4-p00-ob.smtp.rzone.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755764AbaCNI4X (ORCPT ); Fri, 14 Mar 2014 04:56:23 -0400 Received: from fuchsia.localnet (p57A57AA4.dip0.t-ipconnect.de [87.165.122.164]) by smtp.strato.de (RZmta 32.27 DYNA|AUTH) with ESMTPSA id f06362q2E8uLDnE (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (Client did not present a certificate) for ; Fri, 14 Mar 2014 09:56:21 +0100 (CET) From: Michael Schuerig To: linux-btrfs@vger.kernel.org Subject: Re: Incremental backup for a raid1 Date: Fri, 14 Mar 2014 09:56:20 +0100 Message-ID: <1549230.7yEi5AM4H9@fuchsia> In-Reply-To: References: <1564384.fRV1HUkfCq@fuchsia> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Sender: linux-btrfs-owner@vger.kernel.org List-ID: On Friday 14 March 2014 06:42:27 Duncan wrote: > N-way-mirroring is actually my most hotly anticipated feature for a > different reason[2], but for you it would work like this: > > 1) Setup the 3-way (or 4-way if preferred) mirroring and balance to > ensured copies of all data on all devices. > > 2) Optionally scrub to ensure the integrity of all copies. > > 3) Disconnect the backup device(s). (Don't btrfs device delete, this > would remove the copy. Just disconnect.) > > 4) Store the backups. > > 5) Periodically get them out and reconnect. > > 6) Rebalance to update. (Since the devices remain members of the > mirror, simply outdated, the balance should only update, not rewrite > the entire thing.) > > 7) Optionally scrub to verify. > > 8) Repeat steps 3-7 as necessary. Judging from your description, N-way mirroring is (going to be) exactly what I was hoping for. Michael -- Michael Schuerig mailto:michael@schuerig.de http://www.schuerig.de/michael/