From mboxrd@z Thu Jan 1 00:00:00 1970 From: Ric Wheeler Subject: Re: Problem with disk Date: Fri, 05 May 2006 20:51:14 -0400 Message-ID: <445BF302.4050709@emc.com> References: Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII; format=flowed Content-Transfer-Encoding: 7bit Return-path: Received: from mexforward.lss.emc.com ([168.159.213.200]:53080 "EHLO mexforward.lss.emc.com") by vger.kernel.org with ESMTP id S1751184AbWEFAur (ORCPT ); Fri, 5 May 2006 20:50:47 -0400 In-Reply-To: Sender: linux-ide-owner@vger.kernel.org List-Id: linux-ide@vger.kernel.org To: Mark Hahn Cc: David.Ronis@McGill.CA, linux-ide@vger.kernel.org Mark Hahn wrote: >>I would suggest that you should run with the write cache disabled unless >>you can verify working barrier support. >> >> > >this is true, but extremely conservative/paranoid. it makes a lot >of sense if you're handling banking transactions or if you really >see a lot of abrupt power-offs (yank the battery). what are the chances >of a drive failing to write dirty blocks when idle, halting? > > The write cache in modern drives is multiple megabytes - 8 or 16MB is not uncommon. The chances that you have data that is lost on a power failure in the write cache is actually quite high... I agree that most people should not lose too much sleep over this. >don't get me wrong: write barriers are A Good Thing. just that Linux >survived very nicely for many years before such things were bothered with. > > > >>The fact that your drive reports IO errors is also worrying - you might >>just have a bad drive... You can look at drive help with tools like >>smartctl. >> >> > >IO errors trump any concerns for write barriers - there's no need to >even think about barriers or cache settings if the disk is, for instance, >reporting media errors... > > > Agreed again ;-) ric