From mboxrd@z Thu Jan 1 00:00:00 1970 From: Giovanni Tessore Subject: Re: Read errors on raid5 ignored, array still clean .. then disaster !! Date: Sat, 30 Jan 2010 19:44:30 +0100 Message-ID: <4B647E0E.6050609@texsoft.it> References: <4B5F6C73.30707@texsoft.it> <20100127074138.GA9607@maude.comedia.it> <20100129214852.00e565c4@notabene> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <20100129214852.00e565c4@notabene> Sender: linux-raid-owner@vger.kernel.org To: linux-raid@vger.kernel.org Cc: Neil Brown List-Id: linux-raid.ids >>> Is this some kind of bug? >>> >> No >> > I'm not sure I agree. > Hm funny ... I just read now from md's man: "In kernels prior to about 2.6.15, a read error would cause the same effect as a write error. In later kernels, a read-error will instead cause md to attempt a recovery by overwriting the bad block. .... " So things have changed since 2.6.15 ... I was not so wrong to expect "the old behaviour" and to be disappointed. But something important was missing during this change imho: 1) let the old behaviour be the default: add /sys/block/mdXX/max_correctale_read_errors, with default to 0. 2) let the new behaviour be the default, but update mdadm and /proc/mdstat to report read error events. I think the situation is now quite clear. Thanks -- Cordiali saluti. Yours faithfully. Giovanni Tessore