I bought an external HDD a couple of weeks ago, filed about 300GB up by backing up 2 laptops. I need to partition it to add a mac format partition for time machine and my winclone backup. When I try to do this in disk utility, it wont let me. Is there a safe way to do this, possibly with other software? I really don't want to format it because I would need to find somewhere to store the current data on it first (which would be very difficult and time consuming). Thanks, might be a stupid question.