From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from lists.gentoo.org ([140.105.134.102] helo=robin.gentoo.org) by nuthatch.gentoo.org with esmtp (Exim 4.50) id 1EeAGh-0006Gb-8p for garchives@archives.gentoo.org; Mon, 21 Nov 2005 11:55:31 +0000 Received: from robin.gentoo.org (localhost [127.0.0.1]) by robin.gentoo.org (8.13.5/8.13.5) with SMTP id jALBs6L4005509; Mon, 21 Nov 2005 11:54:06 GMT Received: from smtp.gentoo.org (smtp.gentoo.org [134.68.220.30]) by robin.gentoo.org (8.13.5/8.13.5) with ESMTP id jALBor24031852 for ; Mon, 21 Nov 2005 11:50:53 GMT Received: from main.gmane.org ([80.91.229.2] helo=ciao.gmane.org) by smtp.gentoo.org with esmtp (Exim 4.43) id 1EeACD-0007WA-0E for gentoo-dev@lists.gentoo.org; Mon, 21 Nov 2005 11:50:53 +0000 Received: from list by ciao.gmane.org with local (Exim 4.43) id 1EeAB2-0000Rv-W4 for gentoo-dev@gentoo.org; Mon, 21 Nov 2005 12:49:41 +0100 Received: from ip68-230-97-182.ph.ph.cox.net ([68.230.97.182]) by main.gmane.org with esmtp (Gmexim 0.1 (Debian)) id 1AlnuQ-0007hv-00 for ; Mon, 21 Nov 2005 12:49:40 +0100 Received: from 1i5t5.duncan by ip68-230-97-182.ph.ph.cox.net with local (Gmexim 0.1 (Debian)) id 1AlnuQ-0007hv-00 for ; Mon, 21 Nov 2005 12:49:40 +0100 X-Injected-Via-Gmane: http://gmane.org/ To: gentoo-dev@lists.gentoo.org From: Duncan <1i5t5.duncan@cox.net> Subject: [gentoo-dev] Re: Re: implementation details for GLEP 41 Date: Mon, 21 Nov 2005 04:48:47 -0700 Organization: Sometimes Message-ID: References: <20051119170615.GW12982@mail.lieber.org> <200511192042.38836.cshields@gentoo.org> <438000AD.404@gentoo.org> <200511192104.13982.cshields@gentoo.org> <20051120054441.GA17389@curie-int.vc.shawcable.net> <1132498152.22932.4.camel@localhost> <20051120145749.0027af0d@snowdrop.home> Precedence: bulk List-Post: List-Help: List-Unsubscribe: List-Subscribe: List-Id: Gentoo Linux mail X-BeenThere: gentoo-dev@gentoo.org Reply-to: gentoo-dev@lists.gentoo.org Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-7 Content-Transfer-Encoding: 8bit X-Complaints-To: usenet@sea.gmane.org X-Gmane-NNTP-Posting-Host: ip68-230-97-182.ph.ph.cox.net User-Agent: Pan/0.14.2.91 (As She Crawled Across the Table) Sender: news X-Archives-Salt: f350f24a-c59c-40d0-8a79-a39259af4b2f X-Archives-Hash: 1529608b08848c6274a51df3db492fb6 Ciaran McCreesh posted <20051120145749.0027af0d@snowdrop.home>, excerpted below, on Sun, 20 Nov 2005 14:57:49 +0000: > On Sun, 20 Nov 2005 07:49:11 -0700 Lares Moreau > wrote: > | On Sun, 2005-11-20 at 04:29 -0700, Duncan wrote: > | > If the capacity is there, go RAID6 (dual parity RAID5, so two > | > drives can drop out without the thing dieing) with a hot-spare as > | > well, so threex146GB usable. > | > | Is RAID6 production ready? > > RAID6 was only invented because a certain large hardware manufacturer > shipped a bunch of duff disks in one of its drive arrays. In practice > it's not necessary, because if you're taking the kind of damage that > kills multiple drives over a short period then you're going to lose > more than two drives anyway. There's another advantage as well. Single disk failure is common enough to be worrying about or raid5 wouldn't be in consideration. I'm certainly no expert, but from from my research previous to installing here, it is said that raid6 in single failure mode maintains speed, while a raid5 with hot-spare would be responding far slower during the same time, as it brought the hot-spare online and did the rebuild. Thus, if one is going to bother with the hot-spare in the first place, rather than just run the raid5 in degraded mode until a spare can be procured and installed, one might as well put that hot-spare to use making the raid5 a raid6, both protecting against the corner-case of a short-period compound failure, AND maintaining speed during a simple failure. Of course, if that speed maintenance is a a critical factor, then one would hot-spare the raid6 as well, so non-degraded operation could be resumed ASAP, thus again allowing a single failure without degrading speed. -- Duncan - List replies preferred. No HTML msgs. "Every nonfree program has a lord, a master -- and if you use the program, he is your master." Richard Stallman in http://www.linuxdevcenter.com/pub/a/linux/2004/12/22/rms_interview.html -- gentoo-dev@gentoo.org mailing list