From mboxrd@z Thu Jan 1 00:00:00 1970 From: Keld =?iso-8859-1?Q?J=F8rn?= Simonsen Subject: Re: In this partition scheme, grub does not find md information? Date: Tue, 29 Jan 2008 15:48:40 +0100 Message-ID: <20080129144840.GA4621@rap.rap.dk> References: <479EAF42.6010604@pobox.com> <18334.46306.611615.493031@notabene.brown> <479F07E1.7060408@pobox.com> <479F0AAB.3090702@rabbit.us> <479F331F.7080902@msgid.tls.msk.ru> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Content-Disposition: inline In-Reply-To: <479F331F.7080902@msgid.tls.msk.ru> Sender: linux-raid-owner@vger.kernel.org To: Michael Tokarev Cc: Peter Rabbitson , Moshe Yudkowsky , linux-raid@vger.kernel.org List-Id: linux-raid.ids On Tue, Jan 29, 2008 at 05:07:27PM +0300, Michael Tokarev wrote: > Peter Rabbitson wrote: > > Moshe Yudkowsky wrote: > >> > > > It is exactly what the names implies - a new kind of RAID :) The setup > > you describe is not RAID10 it is RAID1+0. > > Raid10 IS RAID1+0 ;) > It's just that linux raid10 driver can utilize more.. interesting ways > to lay out the data. My understandining is that raid10 is different from RAID1+0 Traditional RAID1+0 is composed of two RAID1's combined into one RAID0. It takes 4 drives to make it work. Linux raid10 only takes 2 drives to work. Traditional RAID1+0 only have one way of laying out the blocks. raid10 have a number of ways to do layout, namely the near, far and offset ways, layout=n2, f2, o2 respectively. Traditional RAID1+0 can only do striping of half of the disks involved, while raid10 can do striping on all disks in the far and offset layouts. I looked around on the net for documentation of this. The first hits (on Google) for mkadm did not have descriptions of raid10. Wikipedia describes raid 10 as a synonym for raid1+0. I think there is too much confusion on the raid10 term, and that also the marveleous linux raid10 layouts is a little known secret beyound maybe the circles of this linux-raid list. We should tell others more about the wondersi of raid10. And then I would like a good reference for describing how raid10,o2 works and why bigger chunks work. Best regards keld