[dm-crypt] Open raid1 with luks encryption after a raid re-create

Sven Eschenberg sven at whgl.uni-frankfurt.de
Wed Nov 25 12:49:15 CET 2015


Seems the mail got a little delayed on my side...

You are welcome Luis, good it worked out.

Regards

-Sven


Am 24.11.2015 um 12:15 schrieb Luis Alexandre:
>
> Dear Arno and Sven,
>
> Thanks very much for your support.
>
> I was able to open the copy I made with
>
> tail -c +135266305 /dev/sdx > /dev/sdy
> and
> cryptsetup luksOpen /dev/sdy e1
>
> and have all my data back.
>
> Thanks again for your support.
>
> Best regards,
> Luis
>
> On 23-11-2015 06:26, Arno Wagner wrote:
>> On Mon, Nov 23, 2015 at 04:56:34 CET, Sven Eschenberg wrote:
>>>
>>>
>>> Am 23.11.2015 um 04:35 schrieb Arno Wagner:
>>>> On Sun, Nov 22, 2015 at 23:30:23 CET, Sven Eschenberg wrote:
>>>> [...]
>>>>> Now to your question, once you know the offset of the header:
>>>>> 1.)Setup a loop device from your image (You can use an offset into
>>>>> the image where your loop device starts with sector 0) see --offset
>>>>> in losetup man page.
>>>>
>>>> Ah, yes. That would save copying it.
>>>
>>> That was the plan. In general using dmsetup to create a mapping
>>> manually should work too, if loop device support is missing -
>>> dmsetup is pretty cryptic to use though.
>>
>> "Cryptic" is not good here...
>>
>> I was not aware that losetup allows read-only mappings, or I
>> would probably have looked at it too.
>>
>> Excellent! So I learned something too!
>>
>>>>> Inspect loopdevice if the LUKS Header now is on sector 0
>>>>> 2.)Try a cryptsetup luksopen in readonly mode
>>>>
>>>> Good idea. With that it may be reasonaly safe to work
>>>> with the original disk. I still would make a full
>>>> backup before.
>>>>
>>>> Regards,
>>>> Arno
>>>>
>>>
>>> Well, I thought about using the loop on the file while the physical
>>> disk stays unchanged. Otherwise it would be possible to work on the
>>> physical disk, and keep a safety image. No matter which way one
>>> chooses, always have a safety copy.
>>>
>>> If the disk is having mechanical problems or something similiar one
>>> would of course use 2 images, one 'master binary backup' and the
>>> replica to work on.
>>>
>>> Once mapping and opening works, one can choose to either copy out
>>> the files and backup (usually a good idea) or to create a copy in
>>> the manner you described. Possibly such an image could then be
>>> remerged onto a new clean array, if it is otherwise intact. Not
>>> without some remaining risks though.
>>
>> Indeed. And first things first, lets see whether that header is
>> viable before goping any further.
>>
>> Regards,
>> Arno
>>
>
>
> _______________________________________________
> dm-crypt mailing list
> dm-crypt at saout.de
> http://www.saout.de/mailman/listinfo/dm-crypt


More information about the dm-crypt mailing list