From mboxrd@z Thu Jan 1 00:00:00 1970 From: Keld =?iso-8859-1?Q?J=F8rn?= Simonsen Subject: Re: What's the typical RAID10 setup? Date: Fri, 4 Feb 2011 08:06:13 +0100 Message-ID: <20110204070613.GA3788@www2.open-std.org> References: <20110131192858.GD27952@www2.open-std.org> <4D4718E1.9040607@hardwarefreak.com> <20110131203725.GB2283@www2.open-std.org> <4D475AB5.10600@hardwarefreak.com> <20110203110428.GA26762@www2.open-std.org> <4D4B3DAE.3070502@hardwarefreak.com> 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: <4D4B3DAE.3070502@hardwarefreak.com> Sender: linux-raid-owner@vger.kernel.org To: Stan Hoeppner Cc: Keld =?iso-8859-1?Q?J=F8rn?= Simonsen , Jon Nelson , Mathias =?iso-8859-1?Q?Bur=E9n?= , Roberto Spadim , Denis , Linux-RAID List-Id: linux-raid.ids On Thu, Feb 03, 2011 at 05:43:42PM -0600, Stan Hoeppner wrote: > Keld J=F8rn Simonsen put forth on 2/3/2011 5:04 AM: > > On Mon, Jan 31, 2011 at 06:58:29PM -0600, Stan Hoeppner wrote: > >> Jon Nelson put forth on 1/31/2011 3:27 PM: > >>> Before this goes any further, why not just reference the excellen= t > >>> Wikipedia article (actually, excellent applies to both Wikipedia = *and* > >>> the article): > >>> > >>> http://en.wikipedia.org/wiki/Non-standard_RAID_levels#Linux_MD_RA= ID_10 > >>> > >>> The only problem I have with the wikipedia article is the asserti= on > >>> that Linux MD RAID 10 is non-standard. It's as standard as anythi= ng > >>> else is in this world. > >> > >> Unfortunately there is no organization, no standards body, that de= fines RAID > >> levels.=20 > >=20 > > Well there is an organisation that does just that, namely SNIA. >=20 > I should have qualified that with "defines RAID levels the entire ind= ustry > accepts/adopts". Unfortunately SNIA is not a standards body or worki= ng group, > such as PCI-SIG, or IETF, whose specifications entire industries _do_= accept/adopt. I don't know about SNIA, but I have vast experience with standardisatio= n bodies. I see SNIA as an industry standard standardisation body. I don'= t know how pervasive that organisation is, but their membership list is impressive http://www.snia.org/member_com/member_directory/ - Looks like everybody in the harddisk business is on board. > Please note that the SNIA Disk Data Format document doesn't define RA= ID 10 at > all. Yet there is a single mention of RAID 10 in the entire document= : >=20 > "RAID-1E 0x11 >2 disk RAID-1, similar to RAID-10 but with striping in= tegrated > into array" >=20 > They don't define RAID 10, but they reference it. Thus one can only = assume that > SNIA _assumes_ RAID 10 is already well defined in industry to referen= ce it in > such a manner without previously defining it in the document. >=20 > Does anyone else find this reference to a RAID level omitted in their > definitions a little more than interesting? This RAID 10 omission is= especially > interesting considering that RAID 10 dominates the storage back ends = of Fortune > 1000 companies, specifically beneath databases and high transaction l= oad systems > such as enterprise mail. >=20 > They've omitted defining the one RAID level with the best combination= of high > performance, most resilience, and greatest penetration of the "high e= nd" of > computing in the history of RAID. This begs the question: "Why?" Well RAID1+0 is not the best combination available. I would argue that raid10,f2 is significantly better in a number of areas. > Something smells bad here. Does one of the RAID companies own a pate= nt or > trademark on "RAID 10"? I'll look into this. It just doesn't make a= ny sense > for RAID 10 to be omitted from the SNIA DDF but to be referenced in t= he manner > it is. It looks like they do define all major basic RAID disk layouts. (except raid10,f2 of cause) . RAID1+0 is a derived format, maybe that is out of scope of the DDF standard. 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