[CentOS] more software raid questions

Nataraj incoming-centos at rjl.com
Thu Oct 21 14:17:43 EDT 2010


Nataraj wrote:
> Nataraj wrote:
>   
>> fred smith wrote:
>>   
>>     
>>> Thanks for the additional information.
>>>
>>> I'll try backing up everything this weekend then will take a stab at it.
>>>
>>> someone said earlier that the differing raid superblocks were probably
>>> the cause of the misassignment in the first place. but I have no clue
>>> how the superblocks could have become messed up, can any of you comment
>>> on that? willl I need to hack at that issue, too, before I can succeed?
>>>
>>> thanks again!
>>>
>>>   
>>>     
>>>       
>>>> Nataraj
>>>>     
>>>>       
>>>>         
>> I would first try adding the drives back in with:
>>
>> mdadm /dev/mdN -a /dev/sdXn
>>
>> Again, this is after having stopped the bogus md arrays.
>>
>> If that doesn't work, I would try assemble with a --force option, which 
>> might be a little more dangerous than the hot add, but probably not 
>> much. I can say that when I have a drive fall out of an array I am 
>> always able to add it back with the first command (-a). As I mentioned, 
>> I do have bitmaps on all my arrays, but you can't change that until you 
>> rebuild the raidset.
>>   
>>     
> Note, that if you need to use assemble --force, you must stop the array 
> first and know exactly which drives you want to assemble the array with.
>   
It's possible that my drives go back so easily because of the bitmap.  
You can probably also use --force with the -a option (hot add).
If you use --force, I would make sure that you are specifying the write 
drives/partitions since --force will probably cause whatever partition 
you give it to be used in the array regardless of weather it was in the 
same array before.  So if you use --force, I would check the UUIDs of 
the partitions first and make sure they are the same, since --force 
would allow you to insert one of your md1 partitions into your md0 array.

Nataraj


Nataraj


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