[dm-crypt] Fwd: Cannot wipe header on device

Sven Eschenberg sven at whgl.uni-frankfurt.de
Mon Dec 14 15:46:43 CET 2015


Hi there,

Personally I am wondering what happens if you add seek=1 to the dd 
command line (namely writing the second 4k block) but keeping sync and 
direct flags.

 >> dd if=/dev/zero of=/dev/sdb1 bs=4096 count=1 oflag=sync,direct seek=1

Regards

-Sven


Am 14.12.2015 um 09:44 schrieb Luís de Sousa:
> On 13 December 2015 at 20:52, Milan Broz <gmazyland at gmail.com> wrote:
>>
>> IMHO this operation should print error as well:
>>
>> dd if=/dev/zero of=/dev/sdb1 bs=4096 count=1 oflag=sync,direct
>>
>> (note sync is oflag, not conv=...)
>>
>> Anyway, this is not error in cryptsetup...
>>
>> Milan
>
> Hi Milan, thank you for the reply. You can see the output below, there
> is an error indeed.
>
> I understand this is not an issue with cryptsetup, but would anyone
> have suggestions on how to proceed? Is there any hope of "fixing"
> this, e.g. marking this sector as unusable?
>
> Thank you,
>
> Luís
>
> $ sudo dd if=/dev/zero of=/dev/sdb1 bs=4096 count=1 oflag=sync,direct
> dd: error writing ‘/dev/sdb1’: Remote I/O error
> 1+0 records in
> 0+0 records out
> 0 bytes (0 B) copied, 0.00142455 s, 0.0 kB/s
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