Re: Maximizing failed disk replacement on a RAID5 array

[Brad Campbell <brad@fnarfbargle.com>]

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.