Seagate Skyhawk 3TB Surveillance Desktop Internal Hard Disk Drive ( ST3000VX009 )

Western Digital Purple 2TB 3.5-Inch SATA Surveillance Desktop Internal Hard Disk Drive ( WD23PURZ )
Engineered for mainstream surveillance systems
WD AllFrame technology delivers optimizations for write-intensive, low bit-rate, high stream-count workloads typical to mainstream surveillance applications
Supports up to 180TB/yr workload rate and up to 16 bays

WD Purple 1 TB 5400 RPM 3.5-Inch SATA Surveillance Hard Disk Drive ( WD11PURZ )

WD Purple drives are designed to meet the challenges of 24×7 video surveillance recording. These drives are engineered specifically for surveillance to help withstand the elevated heat fluctuations and equipment vibrations within NVR environments. An average desktop drive is built to run for only short intervals, not the harsh 24/7 always-on environment of a high-definition surveillance system. With WD Purple drives, you get reliable, surveillance-class storage that’s tested for compatibility in a wide range of security systems. Exclusive AllFrame technology helps reduce frame loss and improve overall video playback.