From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Jeff Breidenbach" Subject: Re: mdadm break / restore soft mirror Date: Wed, 12 Dec 2007 20:00:39 -0800 Message-ID: References: <05ED21952E28E94E8352836547A6BA37042318B3@achmsx001.hsa.co.uk> <18272.34965.638276.892803@notabene.brown> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <18272.34965.638276.892803@notabene.brown> Content-Disposition: inline Sender: linux-raid-owner@vger.kernel.org To: Neil Brown Cc: Brett Maton , linux-raid@vger.kernel.org List-Id: linux-raid.ids >Proposed solution is to use software raid mirror. Before backup starts, >break the soft mirror unmount and backup partition I use this method for backup once a week. One challenge is drives aren't great at steaming data quickly (for the resync) while also doing a lot of random access. Having a little extra redundancy (think 3 or more drives in the RAID-1) can really help. >If you can be certain that the device that you break out of the mirror >is never altered, then you could add an internal bitmap while the >array is split and the rebuild will go much faster. Is this also a viable speedup for the "kep rotating backup drives through the array" strategy? If so, how much speedup are we talking about? Assume the array changes by 1% before a backup drive gets rotated in again. Jeff