From mboxrd@z Thu Jan 1 00:00:00 1970 From: Keld =?iso-8859-1?Q?J=F8rn?= Simonsen Subject: Re: [PATCH 00/18] Assorted md patches headed for 2.6.30 Date: Thu, 12 Feb 2009 12:16:43 +0100 Message-ID: <20090212111643.GB13786@rap.rap.dk> References: <20090212031009.23983.14496.stgit@notabene.brown> <20090212081148.GD9439@rap.rap.dk> <4993E82D.1020309@fairbairn-family.com> <20090212094604.GA11981@rap.rap.dk> <1e30801732ac82156aef4d99517a92a3.squirrel@neil.brown.name> Mime-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Transfer-Encoding: QUOTED-PRINTABLE Return-path: Content-Disposition: inline In-Reply-To: <1e30801732ac82156aef4d99517a92a3.squirrel@neil.brown.name> Sender: linux-raid-owner@vger.kernel.org To: NeilBrown Cc: Steve Fairbairn , linux-raid@vger.kernel.org List-Id: linux-raid.ids On Thu, Feb 12, 2009 at 09:52:32PM +1100, NeilBrown wrote: > On Thu, February 12, 2009 8:46 pm, Keld J=F8rn Simonsen wrote: > > On Thu, Feb 12, 2009 at 09:13:17AM +0000, Steve Fairbairn wrote: > >> Keld J=F8rn Simonsen wrote: > >> > > >> >I would rather have functionality to convert raid10 to raid5. > >> >raid1 should be depreciated, as raid10,n2 for all purposes is the= same > >> >but better implementation and performance, and raid10,f2 and raid= 10,o2 > >> >are even better. Nobody should use raid1 anymore. > >> > > >> Complete ignorance of raid10 here, but is raid10, bootab= le, > >> like raid1 is? I use raid1 on my root and boot partitions. > > > > AFAIK, raid10,n2 in default mode (superblock etc) is bootable, as i= t > > looks like two copies of a normal FS. I think this was even reporte= d > > on this list at some time. > > > > You are not the only one that does not know much about raid10. I th= ink > > most Linux administrators don't. And other system adminstrators mo= st > > likely don't either. > > > > Maybe we should rename raid10 to raid1? > > > > Raid10 should just be an enhanced raid1. And I understand from Neil= that > > raid10,o2 is mostly done because it is a standard raid1 layout. So = it is > > strange that it is not available with raid1 in Linux. And I also th= ink > > that the raid10,f2 layout is available from some HW raid controller= s, as > > their implementation of raid1. So all what is in raid10 is other pl= aces > > considered raid1 stuff. > > >=20 > The 'offset' layout came about to be able to support a DDF format > which is called: >=20 > 4.2.18 Integrated Offset Stripe Mirroring (PRL=3D11, RLQ=3D01) >=20 > (4.2.18 is the section of the document > PRL is Primary Raid Level > RLQ is Rail Level Qualifier > ) > There is also >=20 > 4.2.17 Integrated Adjacent Stripe Mirroring (PRL=3D 11, RLQ=3D00) >=20 > which is essentially the same as our n2 layout. >=20 > You should see their > 4.3.4 Spanned Secondary RAID Level (SRL=3D03) >=20 > Though. That would be really .. interesting to implement. >=20 >=20 > You can down load the ddf spec at >=20 > http://www.snia.org/tech_activities/standards/curr_standards/ddf/ >=20 > NeilBrown I did look at the spec, and I could not find something that looked like f2. I then sent them a mail suggesting standardizing raid10,f2 - some months ago. No answer (yet...) Am I right that raid10,f2 is not described in their spec? A bit odd. The idea behind raid10,f2 is quite straightforward, and gives good results. Best regards keld -- To unsubscribe from this list: send the line "unsubscribe linux-raid" i= n the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html