From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757471AbXD0WLf (ORCPT ); Fri, 27 Apr 2007 18:11:35 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1757435AbXD0WLf (ORCPT ); Fri, 27 Apr 2007 18:11:35 -0400 Received: from waste.org ([66.93.16.53]:38611 "EHLO waste.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1757471AbXD0WLd (ORCPT ); Fri, 27 Apr 2007 18:11:33 -0400 Date: Fri, 27 Apr 2007 16:57:53 -0500 From: Matt Mackall To: Valerie Henson Cc: Lennart Sorensen , Tomasz K?oczko , Diego Calleja , Christoph Hellwig , Stefan Richter , Jan Engelhardt , Mike Snitzer , Neil Brown , "David R. Litwin" , linux-kernel@vger.kernel.org Subject: Re: ZFS with Linux: An Open Plea Message-ID: <20070427215753.GK11166@waste.org> References: <46238204.9060907@s5r6.in-berlin.de> <20070416145527.GA26863@infradead.org> <20070416210254.d619933c.diegocg@gmail.com> <20070418172519.GA5577@csclub.uwaterloo.ca> <20070427052102.GD20286@nifty> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20070427052102.GD20286@nifty> User-Agent: Mutt/1.5.13 (2006-08-11) Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Apr 26, 2007 at 10:21:02PM -0700, Valerie Henson wrote: > On Wed, Apr 18, 2007 at 01:25:19PM -0400, Lennart Sorensen wrote: > > > > Does it matter that google's recent report on disk failures indicated > > that SMART never predicted anything useful as far as they could tell? > > Certainly none of my drive failures ever had SMART make any kind of > > indication that anything was wrong. > > I saw that talk, and that's not what I got out of it. They found that > SMART error reports _did_ correlate with drive failure. In fact, a certain small set of SMART indicators were a very good sign that a drive would fail. > However, they found that the correlation was not strong enough to make > it economically feasible to replace disks reporting SMART failures, > since something like 70% of disks were still working a year after the > first failure report. Also, they found that some disks failed without > any SMART error reports. Indeed, SMART registered no counts at all for most failures, so on the whole, it can't be said that SMART can predict failures. So: not a good idea to base your backup scheme on SMART warnings, but not entirely useless. -- Mathematics is the supreme nostalgia of our time.