Hmm, just assuming the laptop is not to be moved around (it stays where the power plug is
), I would gather from your replies that the external hard drive is most likely to fail as it is more vulnerable than the one inside the laptop case. So I guess I'll just backup my external HDD to the internal one, then backup the internal one to the external HDD if time and storage space is not an issue (shouldn't be with 2TB x 2, right ?). Thanks again for the replies !
PS : I would also select dokk2
's reply as a best answer but I can only choose one