From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from lists.gentoo.org (pigeon.gentoo.org [208.92.234.80]) by finch.gentoo.org (Postfix) with ESMTP id 2A35B1381F3 for ; Tue, 17 Sep 2013 16:34:32 +0000 (UTC) Received: from pigeon.gentoo.org (localhost [127.0.0.1]) by pigeon.gentoo.org (Postfix) with SMTP id 593C4E0C23; Tue, 17 Sep 2013 16:34:25 +0000 (UTC) Received: from mail2.viabit.com (mail2.viabit.com [65.246.80.16]) (using TLSv1 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by pigeon.gentoo.org (Postfix) with ESMTPS id 479FAE0C00 for ; Tue, 17 Sep 2013 16:34:24 +0000 (UTC) Received: from [172.17.29.6] (vpn1.metro-data.com [65.213.236.242]) (using TLSv1 with cipher ECDHE-RSA-AES256-SHA (256/256 bits)) (No client certificate requested) by mail2.viabit.com (Postfix) with ESMTPSA id 3cfVJt6xcdz1hgX for ; Tue, 17 Sep 2013 12:34:22 -0400 (EDT) DKIM-Signature: v=1; a=rsa-sha256; c=simple/simple; d=orlitzky.com; s=mail2; t=1379435663; bh=mWH7LPD9YjzUAoyfyoEwdqEsQd0lwhMfj3Ny28XdKHM=; h=Date:From:To:Subject:References:In-Reply-To; b=fnSEZT5+nsLz+kP+l46sHiERna8R+HqA4dQCU+eSi6rNrR3fcOM2YllsXSMRLWz5v 4oasoVuiUu4wBotHeMo+vrwBQGhUL7lDvk186ddQ0mRLtDInsCElJ4ri8SwMq+oD5L EgdheO8fNahDG1/oW+GSxLiNS5bSi0DYnZAsf5VQ= Message-ID: <5238848D.6050703@orlitzky.com> Date: Tue, 17 Sep 2013 12:34:21 -0400 From: Michael Orlitzky User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:17.0) Gecko/20130909 Thunderbird/17.0.8 Precedence: bulk List-Post: List-Help: List-Unsubscribe: List-Subscribe: List-Id: Gentoo Linux mail X-BeenThere: gentoo-user@lists.gentoo.org Reply-to: gentoo-user@lists.gentoo.org MIME-Version: 1.0 To: gentoo-user@lists.gentoo.org Subject: Re: [gentoo-user] ZFS References: <52382CA4.6090407@libertytrek.org> <523872B7.5040302@orlitzky.com> <523877D3.9020109@libertytrek.org> In-Reply-To: <523877D3.9020109@libertytrek.org> X-Enigmail-Version: 1.5.2 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit X-Archives-Salt: a637f873-693d-48a2-a40d-8f431ed18972 X-Archives-Hash: bb8e5f3c655329e9cf40307ada145247 On 09/17/2013 11:40 AM, Tanstaafl wrote: > On 2013-09-17 11:18 AM, Michael Orlitzky wrote: >> Any controller that claims RAID10 on a server with 6 drive bays should >> be able to put all six drives in an array. But you'll get a three-way >> stripe (better performance) instead of a three-way mirror (better fault >> tolerance). >> >> So, >> >> A B C >> A B C >> >> and not, >> >> A B >> A B >> A B >> >> The former gives you more space but slightly less fault tolerance than >> four drives with a hot spare. > > Sorry, don't understand what you're saying. > > Are you talking about the difference between RAID1+0 and RAID0+1? Nope. Both of my examples above are stripes of mirrors, i.e. 1 + 0. > If not, then please point to *authoritative* docs on what you mean. http://www.snia.org/tech_activities/standards/curr_standards/ddf > Googling on just RAID10 doesn't confuse the issues like you seem to be > doing (probably my ignorance though)... > It's not my fault, the standard confuses the issue =) Controllers that can do multi-mirroring are next to nonexistent, so produce few Google results. You can generally assume that RAID10 with 6 drives is going to give you, A B C A B C so you don't get much more fault tolerance by throwing more drives at it. The controller in Grant's server can do this, I'm sure. For maximum fault tolerance, what you really want is, A B A B A B but, like I said, it's hard to find in hardware. The standard I linked to calls both of these "RAID10", thus the confusion. I forget why I even brought it up. I think it was in order to argue that 4 drives w/ spare is more tolerant that 6 drives in RAID10. To make that argument, we need to be clear about what "RAID10" means.