I have a home sever running Ubuntu server. It has two 12TB drives in it. What I'd like to do is simply run a backup in such a way that the second drive is just an exact duplicate of the first, but without copying the entire drive every single time. My idea is that, say once a month, a script compares the contents of the two drives and only makes adjustments based on what has changed on the first drive.
I realize the better way to organize these drives would be to reformat them together in a RAID pool of some kind, but I don't have a third drive big enough to hold the data I have in order to do that.
Actually, random thought, would it be possible to create a RAID 1 setup using only one drive, move the data in it, then add the second drive to it afterward? I'm a complete noob at setting up RAID in Ubuntu.
rsync, provided by @PerlDuck. Here is an elaborated version of the script, which has exclude option: https://github.com/pa4080/simple-backup-solutions – pa4080 Apr 16 '19 at 22:22