I have a 1TB boot drive and I use CCC to clone it everyday. When I woke up this morning it said my boot drive was almost full. The last time I looked I had about 600gigs free and sure enough the clone drive had about 600 gigs free, and my time capsule showed just about as much free. So what over night could have taken up about 500gigs on my HD? I just ran onyx like I do monthly, and I even verified my disk. Last night I did use bit torrent of 2 music albums about 180mbs. The only thing I have been doing different recently is I have been using lostify to tag my TV shows which are saved on a different hard drive. I chose to option to overwrite the current files but could that have saved the files on the boot drive (where Lostify is running from) somehow? I am about to download Disk Inventory X, to see what could be taking up all the space.