Copying large amount of data,like 300 or 400GB’s from one hdd to another using nautilus or any file manager may fail on some occasions. Using the command rsync will be a better idea to copy large piles of data. This will show the progress percentage and the amount of data copied.
rsync -ah --info=progress2 SOURCE_PATH DESTINATION_PATH
change SOURCE and DESTINATION path according to your needs.
HalfaGeek 