I currently have a Windows 10 pc I built with a SSD for windows/apps and two 3TB HDD's for files. One HDD backs up the other by syncing every night via windows built in commands. I would like to add two more 3TB HDD's to both extend the primary and backup HDD. Is the easiest way to do this to treat the new HDD's as their own primary/backup? Or should I create and add volumes? Maybe even go with a RAID setup? Thoughts are appreciated.