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From: Milan Broz <gmazyland@gmail.com>
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Date: Sun, 13 Dec 2015 20:52:43 +0100
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Subject: Re: [dm-crypt] Fwd: Cannot wipe header on device
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On 12/11/2015 03:56 PM, Lu=EDs de Sousa wrote:
> On 11 December 2015 at 15:34, Milan Broz <gmazyland@gmail.com> wrote:
>>
>> Could you please try to add to dd command: oflag=3Ddirect  and try it ag=
ain?
>>
>=20
> Same result (see below). Thanks for helping in any case.
>=20
> $ sudo dd if=3D/dev/zero of=3D/dev/sdb1 bs=3D4096 count=3D2500 conv=3Dsyn=
c oflag=3Ddirect
> 2500+0 records in
> 2500+0 records out
> 10240000 bytes (10 MB) copied, 1.59072 s, 6.4 MB/s
>=20
> $ 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) =3D 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) =3D -1 EREMOTEIO (Remote I/O error)


IMHO this operation should print error as well:

dd if=3D/dev/zero of=3D/dev/sdb1 bs=3D4096 count=3D1 oflag=3Dsync,direct

(note sync is oflag, not conv=3D...)

Anyway, this is not error in cryptsetup...

Milan