From mboxrd@z Thu Jan 1 00:00:00 1970 From: Brad Campbell Subject: Re: Maximizing failed disk replacement on a RAID5 array Date: Mon, 06 Jun 2011 23:54:41 +0800 Message-ID: <4DECF841.1060906@fnarfbargle.com> References: <4DECF025.9040006@fnarfbargle.com> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: Sender: linux-raid-owner@vger.kernel.org To: Drew Cc: Durval Menezes , linux-raid@vger.kernel.org List-Id: linux-raid.ids On 06/06/11 23:37, Drew wrote: >> Now, if I'm off the wall and missing something blindingly obvious feel free >> to thump me with a clue bat (it would not be the first time). >> >> I've lost 2 arrays recently. 8TB to a dodgy controller (thanks SIL), and 2TB >> to complete idiocy on my part, so I know the sting of lost or corrupted >> data. > I think you've covered the process in more detail, including pitfalls, > then I have. :-) Only catch is where would you find a cheap 2-3TB > drive right now? I bought 10 recently for about $90 each. It's all relative, but I consider ~$45 / TB cheap. > I also know the sting of mixing stupidity and dd. ;-) A friend was > helping me do some complex rework with dd on one of my disks. Being > the n00b I followed his instructions exactly, and him being the expert > (and assuming I wasn't the n00b I was back then) didn't double check > my work. Net result was I backed the MBR/Partition Table up using dd, > but did so to a partition on the drive we were working on. There may > have been some alcohol involved (I was in University), the revised > data we inserted failed, and next thing you know I'm running Partition > Magic (the gnu tools circa 2005 failed to detect anything) to try and > recover the partition table. No backups obviously. ;-) Similar to my dd if=/dev/zero of=/dev/sdb bs=1M count=100 except instead of the target disk, it was to a raid array member that was currently active. To its credit, ext3 and fsck managed to give me most of my data back, even if I had to spend months intermittently sorting/renaming inode numbers from lost+found into files and directories. I'd like to claim Alcohol as a mitigating factor (hell, it gets people off charges in our court system all the time) but unfortunately I was just stupid.