Broken raid 5

Broken raid 5

[L. M. J]

Hi, 

 Very short story : I've created an array on top of another one, so I lost my array and my data. 

 Is there à way to recover RAID 5 meta data on each disk to be able to rebuilt the previous raid 5? 

Thabks
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Re: Broken raid 5

[Benjamin ESTRABAUD]

On 21/05/14 23:05, L. M. J wrote:
> Hi,
>
>   Very short story : I've created an array on top of another one,
I presume that you actually mean that you created an array ontop of the 
disks from another array.

  so I lost my array and my data.
>
>   Is there à way to recover RAID 5 meta data on each disk to be able to rebuilt the previous raid 5?
>
Well, if you used the same metadata version (like 1.2 for instance), the 
"old" metadata would have been overwritten by your new RAID metadata 
(assuming you built the RAID on the same drives/partitions) so that 
would be gone as well.

Even if you were able to rebuild the "previous" RAID (also assuming it 
was a RAID5), if your current RAID build has completed the data would 
have been thoroughly destroyed by the build process and recovery would 
be insanely hard.

> Thabks
>

Regards,
Ben.

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Re: Broken raid 5

[Benjamin ESTRABAUD]

On 22/05/14 19:49, L. M. J wrote:
> On 22 mai 2014 13:16:20 CEST, Benjamin ESTRABAUD <be@mpstor.com> wrote:
>> On 21/05/14 23:05, L. M. J wrote:
>>> Hi,
>>>
>>>    Very short story : I've created an array on top of another one,
>> I presume that you actually mean that you created an array ontop of the
>>
>> disks from another array.
>>
>>   so I lost my array and my data.
>>>
>>>    Is there à way to recover RAID 5 meta data on each disk to be able
>> to rebuilt the previous raid 5?
>>>
>> Well, if you used the same metadata version (like 1.2 for instance),
>> the
>> "old" metadata would have been overwritten by your new RAID metadata
>> (assuming you built the RAID on the same drives/partitions) so that
>> would be gone as well.
>>
>> Even if you were able to rebuild the "previous" RAID (also assuming it
>> was a RAID5), if your current RAID build has completed the data would
>> have been thoroughly destroyed by the build process and recovery would
>> be insanely hard.
>>
>>> Thabks
>>>
>>
>> Regards,
>> Ben.
>
> Strange, answer 1 seems different speech, have a look : http://serverfault.com/questions/499051/mdadm-mdadm-cannot-open-dev-sda1-device-or-resource-busy
>
Hi,

I'm not sure this SO question (how to create a RAID10 with the contents 
from one drive) relates to your problem. The first answer is about 
creating a RAID10 with a device missing (the device that currently holds 
the data), formatting the RAID so that the data from the "missing" RAID 
device can first be copied, and then adding the data to the RAID. This 
is to avoid having to copy any data to an intermediate drive when 
reusing a drive (with valid data) to create a RAID.

Regards,
Ben.

> Thanks
>

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