![Western Digital/HGST, 4TB vs. 6TB helium-filled Ultrastar He6 hard drive](http://www.extremetech.com/wp-content/uploads/2013/11/HGST_6TB_HE6HDD_comparison-300x167.jpg)
Western Digital's HGST subsidiary has announced the commercial availability of the world's first hermetically sealed, helium-filled hard drive, the Ultrastar He6 -- a 6-terabyte monster that, along with being the first helium-filled drive, just happens to be the highest-capacity hard drive in the world.