From mboxrd@z Thu Jan 1 00:00:00 1970 From: Stan Hoeppner Subject: Re: What's the typical RAID10 setup? Date: Thu, 03 Feb 2011 17:43:42 -0600 Message-ID: <4D4B3DAE.3070502@hardwarefreak.com> 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> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: QUOTED-PRINTABLE Return-path: In-Reply-To: <20110203110428.GA26762@www2.open-std.org> Sender: linux-raid-owner@vger.kernel.org To: =?ISO-8859-1?Q?Keld_J=F8rn_Simonsen?= Cc: Jon Nelson , =?ISO-8859-1?Q?Mathias_?= =?ISO-8859-1?Q?Bur=E9n?= , Roberto Spadim , Denis , Linux-RAID List-Id: linux-raid.ids 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 excellent >>> Wikipedia article (actually, excellent applies to both Wikipedia *a= nd* >>> the article): >>> >>> http://en.wikipedia.org/wiki/Non-standard_RAID_levels#Linux_MD_RAID= _10 >>> >>> The only problem I have with the wikipedia article is the assertion >>> that Linux MD RAID 10 is non-standard. It's as standard as anything >>> else is in this world. >> >> Unfortunately there is no organization, no standards body, that defi= nes RAID >> levels.=20 >=20 > Well there is an organisation that does just that, namely SNIA. I should have qualified that with "defines RAID levels the entire indus= try accepts/adopts". Unfortunately SNIA is not a standards body or working= group, such as PCI-SIG, or IETF, whose specifications entire industries _do_ a= ccept/adopt. > http://www.snia.org >=20 > The RAID levels are defined in DDF - a "SNIA" standard. Exactly. It's an SNIA standard. Unfortunately SNIA doesn't carry suff= icient weight to drive full adoption. I commend them for trying though. > http://www.snia.org/tech_activities/standards/curr_standards/ddf/ >=20 > (Info courtesey of Neil Brown) Please note that the SNIA Disk Data Format document doesn't define RAID= 10 at all. Yet there is a single mention of RAID 10 in the entire document: "RAID-1E 0x11 >2 disk RAID-1, similar to RAID-10 but with striping inte= grated into array" They don't define RAID 10, but they reference it. Thus one can only as= sume that SNIA _assumes_ RAID 10 is already well defined in industry to reference= it in such a manner without previously defining it in the document. Does anyone else find this reference to a RAID level omitted in their definitions a little more than interesting? This RAID 10 omission is e= specially interesting considering that RAID 10 dominates the storage back ends of= Fortune 1000 companies, specifically beneath databases and high transaction loa= d systems such as enterprise mail. They've omitted defining the one RAID level with the best combination o= f high performance, most resilience, and greatest penetration of the "high end= " of computing in the history of RAID. This begs the question: "Why?" Something smells bad here. Does one of the RAID companies own a patent= or trademark on "RAID 10"? I'll look into this. It just doesn't make any= sense for RAID 10 to be omitted from the SNIA DDF but to be referenced in the= manner it is. --=20 Stan -- 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