Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751362AbWARCK7 (ORCPT ); Tue, 17 Jan 2006 21:10:59 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751309AbWARCK7 (ORCPT ); Tue, 17 Jan 2006 21:10:59 -0500 Received: from ms-smtp-01-smtplb.tampabay.rr.com ([65.32.5.131]:40139 "EHLO ms-smtp-01.tampabay.rr.com") by vger.kernel.org with ESMTP id S1751362AbWARCK7 (ORCPT ); Tue, 17 Jan 2006 21:10:59 -0500 Message-ID: <43CDA3B0.2030503@cfl.rr.com> Date: Tue, 17 Jan 2006 21:10:56 -0500 From: Phillip Susi User-Agent: Mozilla Thunderbird 1.0.7 (X11/20051010) X-Accept-Language: en-us, en MIME-Version: 1.0 To: Michael Loftis CC: linux-kernel@vger.kernel.org Subject: Re: FYI: RAID5 unusably unstable through 2.6.14 References: <43CD8A19.3010100@cfl.rr.com> <7A7A0F7F294BB08D7CDA264C@d216-220-25-20.dynip.modwest.com> In-Reply-To: <7A7A0F7F294BB08D7CDA264C@d216-220-25-20.dynip.modwest.com> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1384 Lines: 29 Michael Loftis wrote: > What about I said was inaccurate? I never said that it increases > exponentially or anything like that, just that it does increase, which > you've proven. I was speaking in the case of a RAID-5 set, where the > minimum is 3 drives, so every additional drive increases the chance of > a double fault condition. Now if we're including mirrors and > stripes/etc, then that means we do have to look at the 2 spindle case, > but the third spindle and beyond keeps increasing. If you've a 1% > failure rate, and you have 100+ drives, chances are pretty good you're > going to see a failure. Yes it's a LOT more complicated than that. > I understood you to be saying that a raid-5 was less reliable than a single disk, which it is not. Maybe I did not read correctly. Yes, a 3 + n disk raid-5 has a higher chance of failure than a 3 disk raid-5, but only slightly so, and in any case, a 3 disk raid-5 is FAR more reliable than a single drive, and only slightly less reliable than a two disk raid-1 ( though you get 3x the space for only 50% higher cost, so 6x cheaper cost per byte of storage ). - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/