a script that MIGHT undelete an LVM PV you deleted

device=/dev/md2

bytes="4c 56 4d 32 20 30 30 31"
str=""
for b in $bytes; do
    hex=$(echo "$b" | tr "[:lower:]" "[:upper:]")
    dec=$(echo "ibase=16; $hex" | bc)

    ch=$(eval "printf \$'\\x${hex}'")
    str="${str}${ch}"
done

echo "Data to write:"
echo -n "$str" | hexdump -C
# 00000000  4c 56 4d 32 20 30 30 31                           |LVM2 001|
# 00000008

echo "Before:"
dd if=$device bs=1 count=8 skip=536 2>/dev/null | hexdump -C
# 00000000  00 00 00 00 00 00 00 00                           |........|
# 00000008

echo "Writing..."
echo -n "$str" | dd of=$device bs=1 count=8 seek=536

echo "After:"
dd if=$device bs=1 count=8 skip=536 2>/dev/null | hexdump -C
# 00000000  4c 56 4d 32 20 30 30 31                           |LVM2 001|
# 00000008