From mboxrd@z Thu Jan 1 00:00:00 1970 From: John Robinson Subject: Re: feature suggestion to handle read errors during re-sync of raid5 Date: Sat, 30 Jan 2010 19:04:29 +0000 Message-ID: <4B6482BD.6090102@anonymous.org.uk> References: <4B6471A1.2070407@texsoft.it> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <4B6471A1.2070407@texsoft.it> Sender: linux-raid-owner@vger.kernel.org To: Giovanni Tessore Cc: linux-raid@vger.kernel.org List-Id: linux-raid.ids On 30/01/2010 17:51, Giovanni Tessore wrote: > [...] Having the OS > recover and rewrite the sectors makes me feel back in the past, when > under DOS we used PCTools and other utilities to do this recovery stuff > on ST-506 drives .... and this works well on raid, but in sinlge disk > configuration, shouldn't these be data loss? > > I'm confused... how much are modern disks reliable? I think the problem is that modern discs haven't got more reliable, but they have got much, much bigger; "modern" 2G discs had a read error rate of 1 bit per 10^14, and current 2T discs have the same, so while on a 2G disc you could read the whole surface of the disc tens of thousands of times before being likely to get a read error, now it's only tens of times. Someone did recently post links to a formal article analysing this subject to this list, but I can't find it :-( Cheers, John.