Old Disaster Recovery guy here. I recommend three copies of your important photo's, documents, etc. One copy on your home computer, one copy by your home computer (thumb drive, remote hard drive, etc.) and one copy off site. Work with copy on your computer and use external drive copy by your computer as a recovery copy in the event the computer copy fails (hardware issue, user error - mistakenly delete file or photo). Use the offsite copy as a recovery copy in the event both the computer copy and the external drive copy fail (house fire). Do regular backups to all the drives. I would keep at the last the three backups. Hope it helps.