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: Tue, 02 Feb 2010 11:06:12 +0000 Message-ID: <4B680724.8060204@anonymous.org.uk> References: <4B6471A1.2070407@texsoft.it> <4B6482BD.6090102@anonymous.org.uk> <4B65AD05.5050000@anonymous.org.uk> <4B662ED1.3060003@gmail.com> <87r5p556na.fsf@frosties.localdomain> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: Sender: linux-raid-owner@vger.kernel.org To: Mikael Abrahamsson Cc: 'Linux RAID' List-Id: linux-raid.ids On 01/02/2010 16:28, Mikael Abrahamsson wrote: [...] > Since the drive has ECC, it would be interesting to see the amount of > read errors ECC has corrected. Would also be interesting to know if the > drive will rewrite a sector if it's ECC corrected, so that ECC doesn't > have to kick in next time (or if they're actually operating in so narrow > margins that they actually use the ECC constantly because the s/n ratio > is bad and that this is part of the design). I think that's exactly what's going on. There may also be some level of correction above which the drive will transparently rewrite after read, e.g. if the limit for correctability is X bits per sector, it'll automatically rewrite when it's had to correct 90% of X bits, but any less than that is just normal operation. Cheers, John.