Help recovering a RAID set

[Liam Proven]

On 10 May 2012 21:56, Rashkae <ubuntu at tigershaunt.com> wrote:
> On 05/10/2012 03:47 PM, Liam Proven wrote:
>>
>> The RAID in one of my servers died. Sadly, so did the disk with the
>> backup on it when I tried to recover it. As did the disk in my desktop
>> with another backup of all the important files.
>>
>> So, I am trying to recover the data.
>>
>> I used gddrescue to get image copies of the 4 × 40GB drives; they are
>> on a 300GB drive, as partitions sdb5, sdb6, sdb7 and sdb8.
>>
>> I am trying to assemble them with mdadm but it reports that there's no
>> superblock on any of them.
>>
>> Looking at the raw partitions with a hex editor, I can see that there
>> are large slices of empty space at the start of each drive.
>>
>> On sdb5 and sdb6, the data starts at 0xB0000. On sdb7 and sdb8 it
>> starts at 0xAA000.
>>
>> Can anyone suggest how I can prune off the first  720896 bytes of the
>> first 2 partitions and the first 696320 bytes of the second 2?
>>
>> I have other spare drives - I could in principle `dd` the whole
>> partitions onto other media, but I am not fluent enough in dd to skip
>> the first $number blocks...
>>
>
> The version of mdadm that your array was created on probably used the
> superblocks that are store at the end of the device, not the start.  If
> these new paritions aren't exactly the same size as the original hard drives
> (or partitions therefof), that's why mdadm can't find the superblocks.
> I've never recovered a raid array from such a situation, but I would think
> the best thing to do would be the dump the partitions from the original
> drives into a file rather than a new partition.

One of the 3 working drives has since failed completely. This is now
the only remaining copy of the data.


-- 
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