[rtkwe]

Looking at PCPartPicker (no drive shucking) Hitachi drives are at least $.02 more per GB than similar (7200RPM >= 1TB) WD and Seagate drives. Which means a difference of ~$20 per TB of storage, which at 1 pod (180TB) every few weeks means they're saving something on the order of 3.5k every few weeks using the cheaper drives. How much the additional failure rate costs them would be wild speculation, between RMAs/warranties and labor there are lots of assumptions to make, so I'll stop there.

eg:

    Hitachi 0F10311	Deskstar 7K2000 (7200RPM) : $0.059/GB

    Western Digital WD30EFRX RED (5400RPM) : $.044/GB

    Seagate ST3000DM001	(7200RPM) : $.034/GB

http://pcpartpicker.com/parts/internal-hard-drive/#m=19,34,3...