Trying to start keeping backups

[tinpanalley]

I've got about 500GB of music, video I'd like to start backing up, I'd like to go with HDDs. I'm confused with how to create a chain of 2 additional HDDs that get backed up with content without wasting time sitting there copying over the stuff that's new. Can anyone enlighten me with some tried and tested processes?

 

[USAFRet]

I use both..