From owner-freebsd-hackers@FreeBSD.ORG Fri Jun 27 11:43:26 2014 Return-Path: Delivered-To: hackers@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [8.8.178.115]) (using TLSv1 with cipher ADH-AES256-SHA (256/256 bits)) (No client certificate requested) by hub.freebsd.org (Postfix) with ESMTPS id 2B54BD5B for ; Fri, 27 Jun 2014 11:43:26 +0000 (UTC) Received: from h2.funkthat.com (gate2.funkthat.com [208.87.223.18]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (Client CN "funkthat.com", Issuer "funkthat.com" (not verified)) by mx1.freebsd.org (Postfix) with ESMTPS id E4CE024CD for ; Fri, 27 Jun 2014 11:43:25 +0000 (UTC) Received: from h2.funkthat.com (localhost [127.0.0.1]) by h2.funkthat.com (8.14.3/8.14.3) with ESMTP id s5RBhJ1M075817 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=NO); Fri, 27 Jun 2014 04:43:19 -0700 (PDT) (envelope-from jmg@h2.funkthat.com) Received: (from jmg@localhost) by h2.funkthat.com (8.14.3/8.14.3/Submit) id s5RBhJFm075816; Fri, 27 Jun 2014 04:43:19 -0700 (PDT) (envelope-from jmg) Date: Fri, 27 Jun 2014 04:43:19 -0700 From: John-Mark Gurney To: "Michael W. Lucas" Subject: Re: gvinum status? Message-ID: <20140627114318.GE1560@funkthat.com> Mail-Followup-To: "Michael W. Lucas" , hackers@freebsd.org References: <20140625124802.GA61700@bewilderbeast.blackhelicopters.org> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20140625124802.GA61700@bewilderbeast.blackhelicopters.org> User-Agent: Mutt/1.4.2.3i X-Operating-System: FreeBSD 7.2-RELEASE i386 X-PGP-Fingerprint: 54BA 873B 6515 3F10 9E88 9322 9CB1 8F74 6D3F A396 X-Files: The truth is out there X-URL: http://resnet.uoregon.edu/~gurney_j/ X-Resume: http://resnet.uoregon.edu/~gurney_j/resume.html X-TipJar: bitcoin:13Qmb6AeTgQecazTWph4XasEsP7nGRbAPE X-to-the-FBI-CIA-and-NSA: HI! HOW YA DOIN? can i haz chizburger? X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.2.2 (h2.funkthat.com [127.0.0.1]); Fri, 27 Jun 2014 04:43:19 -0700 (PDT) Cc: hackers@freebsd.org X-BeenThere: freebsd-hackers@freebsd.org X-Mailman-Version: 2.1.18 Precedence: list List-Id: Technical Discussions relating to FreeBSD List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Fri, 27 Jun 2014 11:43:26 -0000 Michael W. Lucas wrote this message on Wed, Jun 25, 2014 at 08:48 -0400: > Back in the day, vinum was a big deal. It's been replaced by > gvinum(8). And gvinum is the only in-base way to do OS-based RAID5. Well, there is at least one geom raid5 out there, just not in the base system: http://www.wgboome.org/geom_raid5-html Though doesn't look much up to date... > But I don't hear much about it. > > Is gvinum discouraged or slated for deprecation? Or is it merely less > popular now that everyone's jumped on the ZFS train? The problem w/ raid5 is that unless you have a battery backed cache, or a log, or something, you can end up corrupting your data... So, after a power crash, you have to rebuild all pairty, since you don't know which stripe didn't make it entirely to disk... If you don't rebuild and the parity made it to disk and the data didn't, a future data disk lose will corrupt the data on that stripe... And a rebuild after every power lose is a big cost, plus, what happens if the stress of the rebuild causes a disk to die? w/ ZFS and it's COW and raidz being more like RAID3, you never have to worry about the issues above.. So, if you care about your data, you don't do software RAID5, so what's the point of it then? :) -- John-Mark Gurney Voice: +1 415 225 5579 "All that I will do, has been done, All that I have, has not."