From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-ie0-f174.google.com ([209.85.223.174]:63929 "EHLO mail-ie0-f174.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755117AbaCNOoq (ORCPT ); Fri, 14 Mar 2014 10:44:46 -0400 Received: by mail-ie0-f174.google.com with SMTP id rp18so2634878iec.33 for ; Fri, 14 Mar 2014 07:44:45 -0700 (PDT) Message-ID: <532315E1.3060804@gmail.com> Date: Fri, 14 Mar 2014 10:44:49 -0400 From: Austin S Hemmelgarn MIME-Version: 1.0 To: george@chinilu.com, Duncan <1i5t5.duncan@cox.net>, linux-btrfs@vger.kernel.org Subject: Re: Incremental backup for a raid1 References: <1564384.fRV1HUkfCq@fuchsia> <1549230.7yEi5AM4H9@fuchsia> <5323082B.50600@chinilu.com> In-Reply-To: <5323082B.50600@chinilu.com> Content-Type: text/plain; charset=UTF-8 Sender: linux-btrfs-owner@vger.kernel.org List-ID: On 2014-03-14 09:46, George Mitchell wrote: > Actually, an interesting concept would be to have the initial two drive > RAID 1 mirrored by 2 additional drives in 4-way configuration on a > second machine at a remote location on a private high speed network with > both machines up 24/7. In that case, if such a configuration would > work, either machine could be obliterated and the data would survive > fully intact in full duplex mode. It would just need to be remounted > from the backup system and away it goes. Just thinking of interesting > possibilities with n-way mirroring. Oh how I would love to have n-way > mirroring to play with! That can already be done, albeit slightly differently by stacking btrfs RAID 1 on top of a pair of DRBD devices. Of course, this doesn't provide quite the same degree of safety as your suggestion, but it does work (and DRBD makes the remote copy write-mostly for the local system automatically).