From mboxrd@z Thu Jan 1 00:00:00 1970 From: Nix Subject: Re: RAID tuning? Date: Wed, 14 Jun 2006 16:11:17 +0100 Message-ID: <87zmgfn562.fsf@hades.wkstn.nix> References: <4558af040606121737w1bab008am1110e4e1c2cd8934@mail.gmail.com> <17550.2944.728044.154492@cse.unsw.edu.au> <448E127F.5010708@comcast.net> <448EFCA7.6050603@comcast.net> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: In-Reply-To: (Gordon Henderson's message of "13 Jun 2006 22:38:49 +0100") Sender: linux-raid-owner@vger.kernel.org To: Gordon Henderson Cc: Adam Talbot , Justin Piszcz , linux-raid@vger.kernel.org List-Id: linux-raid.ids On 13 Jun 2006, Gordon Henderson said: > On Tue, 13 Jun 2006, Adam Talbot wrote: >> Can any one give me more info on this error? Pulled from >> /var/log/messages. >> "raid6: read error corrected!!" > > Not seen that one!!! The message is pretty easy to figure out and the code (in drivers/md/raid6main.c) is clear enough. The block device driver has reported a read error. In the old days (pre-2.6.15) the drive would have been kicked from the array for that, and the array would have dropped to degraded state; but nowadays the system tries to rewrite the stripe that should have been there (computed from the corresponding stripes on the other disks in the array), and only fails if that doesn't work. Generally hard disks activate sector sparing and stop reporting read errors for bad blocks only when the block is *written* to (it has to do that, annoying though the read errors are; since it can't read the data off the bad block, it can't tell what data should go onto the spare sector that replaces it until you write it). So it's disk damage, but unless it happens over and over again you probably don't need to be too conerned anymore. -- `Voting for any American political party is fundamentally incomprehensible.' --- Vadik