WD 18TB Ultrastar DC HC550 SATA HDD 7200 RPM Class SATA 6 Gb/s 512MB Cache 3.5": From the manufacturerEnterprise-class Hard DrivesUltrastar SATA SeriesUltrastar hard drives feature up to 10 times the workload rating* of desktop drives and employ advanced technologies for enterprise-class reliability, power efficiency and performance. Designed from the ground up to be an ultra-ro