On 12/14/2015 07:03 AM, TheGerwazy . wrote:

Hi  Phil
Thanks for the message .... but,
In the last version of mdadm I get:

./mdadm --create --raid-devices=8 --level=6 --assume-clean /dev/md7
/dev/mapper/ovsdb1:1024 /dev/mapper/ovsdc1:4096
/dev/mapper/ovsdd1:1024 /dev/mapper/ovsde1:1024
/dev/mapper/ovsdf1:1024 /dev/mapper/ovsdg1:1024
/dev/mapper/ovsdh1:1024 /dev/mapper/ovsdi1:4096
mdadm: cannot open /dev/mapper/ovsdb1:1024: No such file or directory

The final version of that feature requires --data-offset=variable before
the :offset syntax is recognized on the devices.

sudo ./mdadm --create --raid-devices=8 --level=6 --assume-clean

mdadm: array /dev/md7 started.

You're committed now.  I hope it works out for you.

BTW is it possible to find right data offset without superblock on drive ?

Only if the content of that member device has searchable content in a
predictable location.  In practice that means finding the offset of the
first member by locating filesystem magic, or otherwise locating the
transition from all zeros to randomish data.

Good luck.

Phil