From mboxrd@z Thu Jan 1 00:00:00 1970 From: Durval Menezes Subject: Re: Maximizing failed disk replacement on a RAID5 array Date: Wed, 8 Jun 2011 04:47:11 -0300 Message-ID: References: <4DECF025.9040006@fnarfbargle.com> <4DECF841.1060906@fnarfbargle.com> <4DEDB8B7.2070708@fnarfbargle.com> <4DEF258A.8090600@fnarfbargle.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Return-path: In-Reply-To: <4DEF258A.8090600@fnarfbargle.com> Sender: linux-raid-owner@vger.kernel.org To: Brad Campbell Cc: linux-raid@vger.kernel.org, Drew List-Id: linux-raid.ids Hello Brad, On Wed, Jun 8, 2011 at 4:32 AM, Brad Campbell wrote: > On 08/06/11 14:58, Durval Menezes wrote: > >> 1) can I simply skip over these sectors (using dd_rescue or multiple >> dd invocations) when off-line copying the old disk to the new one, >> trusting the RAID5 to reconstruct the data correctly from the other 2 > > Noooooooooooo. As we stated early on, it you do that md will have no idea > that the data missing is actually missing as the drive won't return a read > error. Even if a "repair" (echo "repair" >/sys/block/md1/md/sync_status, checking progress with "cat /proc/mdstat" and completion with "tail -f /var/log/messages | grep md" ) finishes with no errors? > does a repair take long on your machine? I find that a few repair runs > generally gets me enough re-writes to clear the dud sectors and allow an > offline clone. I'm sorry if I did not make myself clear; I've already run both a "repair" on the RAID (see above) and a "smart -t long" on the particular disk... I had about 40 bad sectors before, and now have just 4, but these 4 sectors persist as being marked in error... I think the "RAID repair" didn't touch them. Cheers, -- Durval.