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

Milan Broz gmazyland at gmail.com
Sun Dec 13 20:52:43 CET 2015


On 12/11/2015 03:56 PM, Luís de Sousa wrote:
> On 11 December 2015 at 15:34, Milan Broz <gmazyland at gmail.com> wrote:
>>
>> Could you please try to add to dd command: oflag=direct  and try it again?
>>
> 
> Same result (see below). Thanks for helping in any case.
> 
> $ sudo dd if=/dev/zero of=/dev/sdb1 bs=4096 count=2500 conv=sync oflag=direct
> 2500+0 records in
> 2500+0 records out
> 10240000 bytes (10 MB) copied, 1.59072 s, 6.4 MB/s
> 
> $ sudo cryptsetup -y -v luksFormat /dev/sdb1

...

strace shows that it is really IO error reported on write:

open("/dev/sdb1", O_RDWR|O_EXCL|O_SYNC|O_DIRECT) = 6
...
write(6, "\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0"..., 4096) = -1 EREMOTEIO (Remote I/O error)


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


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