HDD SATA 4TB 5900RPM 6GB/S/64MB ST4000VN008 SEAGATE

Optimized for NAS with AgileArray. AgileArray is built for dual-plane balancing and RAID optimization in multi-bay environments with the most advanced power management possible. 
High performance means no lag times or downtime for users during high traffic time for the NAS. Seagate leads the competition with the highest performance in NAS-class drives.
Rotational Vibration (RV) mitigation. First in its class of drives to include RV sensors to maintain high performance in multi-drive NAS enclosures. Get ahead with more cache. IronWolf provides high-cache options allowing your NAS to serve data faster.
Do more with multi-user technology. Enables user workload rate of 180TB/year. Multiple users can confidently upload and download data to the NAS server, knowing it can handle the workload, whether you’re a creative professional or small business.
Designed for always on, always accessible 24×7 performance. Access your data on your NAS any time, remotely or on site.