From owner-freebsd-geom@FreeBSD.ORG Mon Jul 10 09:45:29 2006 Return-Path: X-Original-To: freebsd-geom@freebsd.org Delivered-To: freebsd-geom@freebsd.org Received: from mx1.FreeBSD.org (mx1.freebsd.org [216.136.204.125]) by hub.freebsd.org (Postfix) with ESMTP id 91C0C16A4DA for ; Mon, 10 Jul 2006 09:45:29 +0000 (UTC) (envelope-from arne_woerner@yahoo.com) Received: from web30310.mail.mud.yahoo.com (web30310.mail.mud.yahoo.com [68.142.200.103]) by mx1.FreeBSD.org (Postfix) with SMTP id 9C70143D76 for ; Mon, 10 Jul 2006 09:45:19 +0000 (GMT) (envelope-from arne_woerner@yahoo.com) Received: (qmail 1541 invoked by uid 60001); 10 Jul 2006 09:45:15 -0000 DomainKey-Signature: a=rsa-sha1; q=dns; c=nofws; s=s1024; d=yahoo.com; h=Message-ID:Received:Date:From:Subject:To:In-Reply-To:MIME-Version:Content-Type:Content-Transfer-Encoding; b=scEE9jlYgzPiSplJIC1bgUq5VcSdwm+mpR5AK83S7FhCkLPb9lOn3QRGSoVFLrHEx7vqTASpD3p58cESnfGXV/I3yEh2Q5CvmREmPtVy+nLzj+iU9O8hBIaa74l6YZa+KHkoq1xbRqYLt5MgxarqQx7CgjNzO2jmVqKwMBEwJhM= ; Message-ID: <20060710094515.1539.qmail@web30310.mail.mud.yahoo.com> Received: from [213.54.82.46] by web30310.mail.mud.yahoo.com via HTTP; Mon, 10 Jul 2006 02:45:15 PDT Date: Mon, 10 Jul 2006 02:45:15 -0700 (PDT) From: "R. B. Riddick" To: Stanislav Sedov , freebsd-geom@freebsd.org In-Reply-To: <20060710133121.1836230d@localhost> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Transfer-Encoding: 8bit Cc: Subject: Re: new class / geom_raid5 X-BeenThere: freebsd-geom@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: GEOM-specific discussions and implementations List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Mon, 10 Jul 2006 09:45:29 -0000 --- Stanislav Sedov wrote: > На Thu, 6 Jul 2006 15:42:09 -0700 (PDT) > "R. B. Riddick" записано: > > My proposal for > > geom_raid5 > > is ready so far... > > > > If somebody wants to test it, he or she can download it from > > http://home.tiscali.de./cmdr_faako/geom_raid5.tbz > > How do you handle data recovery in case of crash of one of providers? > Hmm... As far as I understood the RAID5 idea, it is the following "trick": A XOR B XOR C = P A = P XOR B XOR C B = P XOR A XOR C C = P XOR A XOR B > All raid5 implemetations use different ECC algorithms for this, > like Reed-Solomon codes etc. > Hmm... I dont know so much about coding theory... I know that ECC means "error correction code" and I think the above formula describes an ECC, that can correct a missing bit, if we already know which bit is missing... E. g.: If we have the valid codewords 10 and 01, then we cannot say what 11 means, unless somebody tells us the second bit is a really very bad bit. > I haven't looked deeply into the code, but it seems there is no > any such algrithms implemeted there. Do you just duplicate data > on all providers? > Hmm... "duplicate data on all providers"... That sounds like a RAID1 / MIRROR... I am sorry, that my code is so bad, that it looks like MIRROR code... Maybe you should have a look at my newest version (I changed some things, but it is still mostly untested)? I have heard, that code inspection and tests should be done by somebody, who did not write it... So I would be glad, if somebody helps me here (of course I will do some tests, too, although I am a little bit annoyed by the BIOS-beeps already)... Should I use more but shorter functions? -Arne __________________________________________________ Do You Yahoo!? Tired of spam? Yahoo! Mail has the best spam protection around http://mail.yahoo.com