The Western Digital WD85PURZ is a specialized surveillance hard drive from the WD Purple series, designed to handle the demanding requirements of 24/7 recording in NVR environments. With a capacity of 8 TB, it provides ample space for high-definition footage, supporting up to 64 HD cameras and operating efficiently in systems with up to 16 drive bays. The drive utilizes Conventional Magnetic Recording (CMR) technology and a 256 MB cache to maintain a sustained transfer rate of up to 215 MB/s, ensuring that data flows smoothly during continuous write operations. To prevent the frustration of missing footage, this 3.5-inch drive incorporates AllFrame technology, which reduces frame loss and improves the quality of video playback. It is built for long-term reliability with a workload rating of 180 TB per year and a mean time between failures of up to 1 million hours. The hardware includes tarnish-resistant components to protect the internal circuitry, while the 5640 RPM rotational speed balances performance with the thermal stability needed for constant operation between 0°C and 65°C.