I tried using dd to clone the compact flash
dd if=dev/sda  of=/image.img  # copy original compact flash to a file 
dd if=/image.img if=dev/sda    #copy file to target compact flash

but when I use the cloned compact flash I get an error that it can't read(?) the mounted drive:
mount -tgnx6 /dev/hd0t179 /d0
  mount: can't mount /d0 (type qnx6)
  mount: possible reason: read only file system.

What am I missing when making the clone?