My book for photo storae only not backup

WD External Drives External Drives for Mac
1

CAN I JUST USE MY BOOK FOR IPHOTO ONLY MY IMAC HAS NO MORE SPACE FOR STORAGE  I DON’T NEED BACKUP. I ALREADY HAVE BACKUP ON OTHER DEVICE 

2

Never trust one drive to store important data internal or external no matter who makes it. Get 2 drives so you have a copy, that is a backup.

Joe