From mboxrd@z Thu Jan 1 00:00:00 1970 From: Gionatan Danti Subject: Re: RAID 10 far and offset on-disk layouts Date: Fri, 27 Dec 2013 16:16:12 +0100 Message-ID: <52BD99BC.8000205@assyoma.it> References: <52BD8EDD.10809@assyoma.it> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <52BD8EDD.10809@assyoma.it> Sender: linux-raid-owner@vger.kernel.org To: linux-raid@vger.kernel.org List-Id: linux-raid.ids > It does not matter (except to people writing MD-specific tools). > There is nothing special as to the ordering of drives or chunks > on drives. Also reliability is a *statistical* property not a > geometric one... Uhm, why it don't matter? For clarity, let me redraw the two schemas: 1) A1 A2 A3 A4 .. .. .. .. A4 A1 A2 A3 2) A1 A2 A3 A4 .. .. .. .. A2 A1 A4 A3 Schema n.1 will fail on any adjacent disk failure. Eg: 1 & 2, 2 & 3, 3 & 4, 4 & 1. On the other hand, schema n.2 will become inactive only when 1 & 2 or 3 & 4 disk fail, but not, for example, when 2 & 3 or 1 & 4 fail. Or I misunderstand something? > That "consecutive two-disk failures" is really funny! Er, my English is not very good :p I really was talking about adjacent disk failures. Sorry! > If two-paired-disk failure in RAID10 bother you, try RAID14: > > http://www.sabi.co.uk/blog/13-two.html#131213 > > Warning: that does not come at no cost :-). Thank you very mych for the link! I need some time to read it carefully... Regards. -- Danti Gionatan Supporto Tecnico Assyoma S.r.l. - www.assyoma.it email: g.danti@assyoma.it - info@assyoma.it GPG public key ID: FF5F32A8