From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S965082AbWECECa (ORCPT ); Wed, 3 May 2006 00:02:30 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S965081AbWECECa (ORCPT ); Wed, 3 May 2006 00:02:30 -0400 Received: from [213.184.169.90] ([213.184.169.90]:42759 "EHLO raad.intranet") by vger.kernel.org with ESMTP id S965059AbWECEC3 (ORCPT ); Wed, 3 May 2006 00:02:29 -0400 From: Al Boldi To: Neil Brown Subject: Re: [PATCH 009 of 11] md: Support stripe/offset mode in raid10 Date: Wed, 3 May 2006 07:00:23 +0300 User-Agent: KMail/1.5 Cc: linux-raid@vger.kernel.org, linux-kernel@vger.kernel.org, Andrew Morton References: <20060501152229.18367.patches@notabene> <200605021938.45254.a1426z@gawab.com> <17495.62433.136481.543828@cse.unsw.edu.au> In-Reply-To: <17495.62433.136481.543828@cse.unsw.edu.au> MIME-Version: 1.0 Content-Type: text/plain; charset="windows-1256" Content-Transfer-Encoding: 7bit Content-Disposition: inline Message-Id: <200605030700.23515.a1426z@gawab.com> Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Neil Brown wrote: > On Tuesday May 2, a1426z@gawab.com wrote: > > NeilBrown wrote: > > > The "industry standard" DDF format allows for a stripe/offset layout > > > where data is duplicated on different stripes. e.g. > > > > > > A B C D > > > D A B C > > > E F G H > > > H E F G > > > > > > (columns are drives, rows are stripes, LETTERS are chunks of data). > > > > Presumably, this is the case for --layout=f2 ? > > Almost. mdadm doesn't support this layout yet. > 'f2' is a similar layout, but the offset stripes are a lot further > down the drives. > It will possibly be called 'o2' or 'offset2'. > > > If so, would --layout=f4 result in a 4-mirror/striped array? > > o4 on a 4 drive array would be > > A B C D > D A B C > C D A B > B C D A > E F G H > .... Yes, so would this give us 4 physically duplicate mirrors? If not, would it be possible to add a far-offset mode to yield such a layout? > > Also, would it be possible to have a staged write-back mechanism across > > multiple stripes? > > What exactly would that mean? Write the first stripe, then write subsequent duplicate stripes based on idle with a max delay for each delayed stripe. > And what would be the advantage? Faster burst writes, probably. Thanks! -- Al