Check the link bellow for help.
How to copy or move files or folders to a different hard drive on a Mac
http://wdc.custhelp.com/app/answers/detail/a_id/1199/session/L2F2LzEvc25vLzEvdGltZS8xMzI3MjUzMzgwL3NpZC94QTZjNU9Paw%3D%3D