I did this last summer (rebuilt w/ --assemble --force) and it worked ok.

For a drive that's really failed, you can dd as much of it as you can to 
a new drive, then run fsck on the new drive, then add it back in w/ 
--assemble --force. That worked for me as well IIRC. It did lose 
whatever wasn't able to be read w/ dd from the old drive though.

Given that 2 drives went at once, consider that the i/o card or MB (or 
PS) might be having issues. That was the case with the incident last 
summer (replaced i/o card, then MB was failing).

Joe Fleming wrote:
> That's exactly what I want to do here; just pull up one of the drives 
> long enough that I can get the data off it. I suspect one of the drives 
> really did fail, I've been waiting for it to happen in fact. But since 
> the other drive claims to have failed at the EXACT same time, I really 
> don't think that it did.
> 
> I saw the --force option but there's no indication that it wasn't going 
> to rebuild the array. The assemble option might simply imply that 
> though.... it does say "This usage assembles one of more raid arrays 
> from pre-existing components" which sounds promising enough.
> 
> I think you've described exactly what I was trying to do; assemble (NOT 
> rebuild) and copy. Thanks!
> 
> -Joe
>> I've had luck in the past recovering from a multi-drive failure, where 
>> the other failed drive was not truly dead but rather was dropped 
>> because of an IO error caused by a thermal calibration or something 
>> similar.  The trick is to re-add the drive to the array and using the 
>> option to force it NOT to try to rebuild the array.  This used to be 
>> an require several options like --really-force and --really-dangerous 
>> but now I think its just something like --assemble --force /dev/md0. 
>> This forces the array to come back up to its degraded (still down 1 
>> disk) state.  If possible replace the degraded disk or copy your data 
>> off before the other flakey drive fails.
>> ------------------------------------------------------------------------
>>
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-- 
-Eric 'shubes'

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