If the drive is not mounted, theOk now can you do add if=/dev/zero of=/dev/da0
with a drive that you don't have a backup of the data (assuming it is an usb external that is named da0, rename with what you have), of course do not mount it. I am not interesting to test it myself since I care about my data. Your answer make no sense since I was talking about accessing the raw devices not the filesystem.
dd
command is not going to work, and the raw device cannot be accessed, either. Output from dd
will be redirected to stderr(4) in that case.