When you create a backup system for your data, duplication is the best course of action. I don’t mean duplicating the files—that’s a requirement—but duplicating the destinations to which files are bound.
Every form of backup media is destined to fail, and despite high reliability from cloud-backup services, you can’t put all your faith that any of them will always be perfect. Even a system with “five nines” of reliability (99.999 percent) may suffer a loss, and the universe might pick you to experience that loss.
The rule of thumb is summarized as 3-2-1: three copies of your data, two of them local, and one offsite. One copy is your live version on your active drives; one can be a Time Machine backup; and the offsite one can be either a cloud backup, or your files stored somewhere securely and regularly rotate with the local backup.
