From owner-freebsd-hardware@FreeBSD.ORG Tue Jan 15 16:07:23 2013 Return-Path: Delivered-To: freebsd-hardware@freebsd.org Received: from mx1.freebsd.org (mx1.FreeBSD.org [8.8.178.115]) by hub.freebsd.org (Postfix) with ESMTP id 6423D50F for ; Tue, 15 Jan 2013 16:07:23 +0000 (UTC) (envelope-from landsidel.allen@gmail.com) Received: from mail-vb0-f43.google.com (mail-vb0-f43.google.com [209.85.212.43]) by mx1.freebsd.org (Postfix) with ESMTP id 24ACD279 for ; Tue, 15 Jan 2013 16:07:22 +0000 (UTC) Received: by mail-vb0-f43.google.com with SMTP id fs19so275092vbb.16 for ; Tue, 15 Jan 2013 08:07:22 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20120113; h=x-received:message-id:date:from:user-agent:mime-version:to:subject :references:in-reply-to:x-forwarded-message-id:content-type; bh=4yUtwzimCRFa4yWzbCaxBjCKtxIc1BJpz6BP+dXUTqQ=; b=bT4fVi0Ulhm9RkICHoh/nGDhTwaNQKyGluc7ecK21nsQPVVTRwIytDNfuRTxtfakx7 x7aeoD5RGEujXTbTrGkkifmMbMFOrSUK4OR7IMGiubaooyawb/ZFI4cveqLeTCfcu3n8 l71TKVXyh1U32dA40aEE6AbQ58E7Ztz+OaO+otA3GfSV5uh29H+3g8d97ebMBA/fTj8H 0vNsBs0Qe36iAZ3VGmqBOzNNQ8hBUoUkYpXPwTgcUBQs/JOkTpLB7LRjeTGlE6/GnkqL aftFHkuXQZUq9WOkXxhrPvnZJLZQCeVBxGTueoAoVwmxmPj4UIGqAhXpOW4xk/Z8RCfn MU7Q== X-Received: by 10.52.22.207 with SMTP id g15mr91632011vdf.61.1358266041996; Tue, 15 Jan 2013 08:07:21 -0800 (PST) Received: from [192.168.130.0] (c-66-30-48-132.hsd1.nh.comcast.net. [66.30.48.132]) by mx.google.com with ESMTPS id w4sm8745654vdj.21.2013.01.15.08.07.20 (version=TLSv1 cipher=ECDHE-RSA-RC4-SHA bits=128/128); Tue, 15 Jan 2013 08:07:21 -0800 (PST) Message-ID: <50F57EB5.1060801@gmail.com> Date: Tue, 15 Jan 2013 11:07:17 -0500 From: Allen Landsidel User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:17.0) Gecko/20130107 Thunderbird/17.0.2 MIME-Version: 1.0 To: freebsd-hardware@freebsd.org Subject: Fwd: Re: bin/166589: atacontrol(8) incorrectly treats RAID10 and 0+1 the same References: <50F57C0D.1010608@FreeBSD.org> In-Reply-To: <50F57C0D.1010608@FreeBSD.org> X-Forwarded-Message-Id: <50F57C0D.1010608@FreeBSD.org> Content-Type: text/plain; charset=KOI8-R; format=flowed Content-Transfer-Encoding: 7bit X-Content-Filtered-By: Mailman/MimeDel 2.1.14 X-BeenThere: freebsd-hardware@freebsd.org X-Mailman-Version: 2.1.14 Precedence: list List-Id: General discussion of FreeBSD hardware List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Tue, 15 Jan 2013 16:07:23 -0000 http://www.freebsd.org/cgi/query-pr.cgi?pr=166589&cat= Can somebody else talk some sense into this guy? I'm losing my temper. -------- Original Message -------- Subject: Re: bin/166589: atacontrol(8) incorrectly treats RAID10 and 0+1 the same Date: Tue, 15 Jan 2013 17:55:57 +0200 From: Alexander Motin To: Allen Landsidel CC: bug-followup@FreeBSD.org Their on-disk formats are identical. Even if RAID BIOS supports RAID0+1, there is no problem to handle it as RAID10 at the OS level. That gives better reliability without any downsides. I think there is much higher chance that inexperienced user will choose RAID0+1 by mistake, then experienced wish do to it on intentionally. Do you know any reason why RAID0+1 can't be handled as RAID10? On 15.01.2013 17:28, Allen Landsidel wrote: > Most devices typically only support one level or the other, but not > both. I don't "Insist that it should exist", it *does* exist. Both > levels do, and they are not the same thing. > > As for why it should be "available" to the user, I think that's a pretty > silly question. If their hardware supports one or both levels, they > should be available to the user -- and called by their correct names. > > On 1/15/2013 03:12, Alexander Motin wrote: >> That is clear and I had guess you mean it, but why do you insist that >> such RAID0+1 variant should even exist if it has no benefits over >> RAID10, and why it should be explicitly available to user? >> >> On 15.01.2013 04:51, Allen Landsidel wrote: >>> They are not variants in terminology, they are different raid levels. >>> Raid0+1 is two RAID-0 arrays, mirrored into a RAID-1. if one of the >>> disks fails, that entire RAID-0 is offline and must be rebuilt, and all >>> redundancy is lost. A RAID-10 is composed of N raid-1 disks combined >>> into a RAID-0. If one disk fails, only that particular RAID-1 is >>> degraded, and the redundancy of the others is maintained. >>> >>> 0+1 cannot survive two failed disks no matter how many are in the >>> array. 10 can survive half the disks failing, if it's the right half. >>> >>> This is something people who've never used more than 4 disks fail to >>> grasp, but those of us with 6 (or many many more) know very well. >>> >>> On 1/14/2013 21:46, Alexander Motin wrote: >>>> There could be variants in terminology, but in fact for most of users >>>> they are the same. If you have opinion why they should be treated >>>> differently, please explain it. > -- Alexander Motin