clone of openbsd by dd

hi all .

i do backup hard disk by booting archlinux's install USB memory and dd .

because one liner ' while true ; do ; sleep 10 ; killall -USR1 dd ;
done '
is effective on another screen ( alt + F2 ) .
so i know the progressive state of dd on original screen ( alt + F1) .

reversely i do archlinux's hard disk by booting openbsd's install USB
memory and dd ( espetially it is made by btrfs ) .

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regards