voici (pour info mon disque dur externe USB est neuf) :
Bloc de code:
-bash-3.2# diskutil eraseDisk jhfs+ Clone gpt disk21
Started erase on disk21
Unmounting disk
Creating the partition map
Waiting for partitions to activate
Formatting disk21s2 as Mac OS Extended (Journaled) with name Clone
Initialized /dev/rdisk21s2 as a 931 GB case-insensitive HFS Plus volume with a 81920k journal
Mounting disk
Finished erase on disk21
-bash-3.2#