If you pay any attention to hard drive vendors you are aware that the three big names are Seagate, Western Digital, and Hitachi.  Hitachi is known for being the first to market with a 3TB enterprise class drive, the Ultrastar 7K3000 back in January 2011 and has many successful hard drive launches prior to that.  Lately they have also focused on the external back up market with their Touro line of hard drives.