I have a 3 TB internal harddrive and i figured that it would last me a long time. well its filled up and i have no clue how. i do have a couple duplicated movies but only about 40GB in movies all together. and about 30GB in music and 70GB in pictures. so i can't for the life of me figure out why my harddrive is filling up. any ideas? ive already looked at my stats and all i can find is it saying how much is used and not used. when i look at what is using what it all looks right. ive tried a duplicate file finder but that only worked for music for some reason and there were like 70,000 files i would have to manually delete. i don't know what else to do.
You could try the GNOME disk usage analyzer https://help.ubuntu.com/community/Baobab, it has helped me to easily identify the folders that contain more information and dig into the problem graphically.
You can analyze the full partition or just your home directory to find out where is the root cause of your problem.