 It is here, the largest hard disk drive you will find on the market today clocks in at a massive 20 terabytes. Also, there are 24 terabytes external hard disk drives. However, Seagate's 18 terabyte iron wolf drive has proven to be the most stable and will get the job done. If you absolutely need the storage to house hundreds of games or thousands of hours of video footage, this is the perfect drive for you. But did you know?