WD 2TB Purple 256MB SATA 6Gb/s(WD22PURZ)

Engineered specifically for mainstream surveillance systems.
AllFrame technology delivers optimizations for write-intensive, low bit-rate, high stream-count workloads typical to mainstream surveillance applications.
Supports up to 180 TB/yr workload rate². | ²Workload Rate is defined as the amount of user data transferred to or from the hard drive. Workload Rate is annualized (TB transferred ✕ (8760 / recorded power-on hours)). Workload Rate will vary depending on your hardware and software components and configurations.
1TB¹ through 3TB support up to eight bays; 4TB and above support up to 16 bays and employ tarnish-resistant components for harsher environments.
¹As used for storage capacity, 1TB = one trillion bytes. Actual user capacity may be less, depending on operating environment.