In what can only be described as the hard drive equivalent of Game of Thrones, Western Digital's HGST has announced the world's first 10-terabyte hard drive: the helium-filled Ultrastar He10. This comes just a few weeks after Seagate announced initial availability of its 8TB air-filled hard drive, which at the time was the largest hard drive in the world. There's no word on pricing yet but Western Digital says, somewhat unbelievably, that the 10TB drive will have the lowest cost-per-gigabyte and power consumption-per-gigabyte of any drive on the market.