/g/ - Technolo/g/y

Good evening, my dear /g/irls!
I have one particular directory on my hard drive that contains about a terabyte of some utmost important content (images, minecraft worlds, porn, notes, books, zines, diaries, websites backups, videos, scripts, etc). I also have several other HDDs and SSD lying around. Now I would like to back up that directory from the current HDD to all the other drives.
Also, sometimes modify the directory contents (delete, add and [b]EDIT[\b] files).
Friends, please advice me a software to make and synchronize this kind of backups. I would connect the backup drives once a month to sync manually, so I don't need any kind of storage array, RAID or something. Also I am too dumb to google it on my own.