From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mo4-p00-ob.smtp.rzone.de ([81.169.146.162]:50357 "EHLO mo4-p00-ob.smtp.rzone.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752732AbaCOLfe (ORCPT ); Sat, 15 Mar 2014 07:35:34 -0400 Received: from fuchsia.localnet (p5DE8D06B.dip0.t-ipconnect.de [93.232.208.107]) by smtp.strato.de (RZmta 32.27 DYNA|AUTH) with ESMTPSA id f06362q2FBZUQIS (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (Client did not present a certificate) for ; Sat, 15 Mar 2014 12:35:30 +0100 (CET) From: Michael Schuerig To: linux-btrfs@vger.kernel.org Subject: Re: Incremental backup for a raid1 Date: Sat, 15 Mar 2014 12:35:30 +0100 Message-ID: <1789445.UA8sCrE2Cn@fuchsia> In-Reply-To: <53224D57.8020308@chinilu.com> References: <1564384.fRV1HUkfCq@fuchsia> <2106363.nA97oxn4hn@fuchsia> <53224D57.8020308@chinilu.com> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Sender: linux-btrfs-owner@vger.kernel.org List-ID: On Thursday 13 March 2014 17:29:11 George Mitchell wrote: > I currently use rsync to a separate drive to maintain a > backup copy, but it is not integrated into the array like n-way would > be, and is definitely not a perfect solution. Could you explain how you're using rsync? I was just about to copy a btrfs filesystem to another disk. That filesystem has several subvolumes and about 100 snapshots overall. Owing to COW, this amounts to about 1.2TB. However, I reckon that rsync doesn't know anything about COW and accordingly would blow up my data immensely on the destination disk. How do I copy a btrfs filesystem preserving its complete contents? How do I update such a copy? Yes, I want to keep the subvolume layout of the original and I want to copy all snapshots. I don't think send/receive is the answer, but it's likey I don't understand it well enough. I'm concerned, that a send/receive-based approach is not robust against mishaps. Consider: I want to incrementally back-up a filesystem to two external disks. For this I'd have to for each subvolume keep a snapshot corresponding to its state on the backup disk. If I make any mistake in managing these snapshots, I can't update the external backup anymore. Also, I don't understand whether send/receive would allow me to copy/update a subvolume *including* its snapshots. Things have become a little more complicated than I had hoped for, but I've only been using btrfs for a couple of weeks. Michael -- Michael Schuerig mailto:michael@schuerig.de http://www.schuerig.de/michael/