SATA 6 Gb/s 512MB Cache WD 16TB Ultrastar DC HC550 SATA HDD 7200 RPM Class SATA 3.5": From the producer Hard drives of the enterprise class Ultrastar SATA Series Ultrastar hard drives use cutting-edge technologies for enterprise-class performance, power efficiency, and dependability, and they have up to ten times the workload rating* of desktop drives. Originally intended to be an ultra-ro