WD Purple 4TB Surveillance Hard Drive WD43PURZ: features and who it suits

The WD Purple 4TB (model WD43PURZ) is an internal 3.5-inch hard drive made for video surveillance recorders. Instead of the short, bursty use of a desktop PC, a security system writes video around the clock, and this drive is built for that pattern. Here is what its specifications mean and what to confirm before fitting one.

Why surveillance drives are different

A typical desktop drive is designed to run for a few hours at a time, reading and writing in unpredictable bursts. A network video recorder (NVR) or digital video recorder (DVR) behaves differently: it writes several continuous streams at once, day and night, and only occasionally reads them back. Western Digital describes the Purple range as engineered for 24x7 recording and for the heat changes and vibration found inside recorder enclosures, where several drives often sit side by side.

What AllFrame technology does

AllFrame is Western Digital's name for firmware tuning aimed at write-heavy, low bit-rate video with many simultaneous streams. The brand says it helps reduce frame loss and improve playback. In general terms, a normal drive may pause to retry a difficult read or write, and a recorder can lose frames during that pause. Surveillance firmware is typically set up to limit those delays, because dropped video is worse than a slightly less thorough error-recovery attempt.

Capacity, cache and interface

This model stores 4TB and connects over SATA 6 Gb/s, the standard interface on current recorders and PCs. It has a 256 MB cache, a buffer that helps smooth out the constant stream of writes. The drive is a standard 3.5-inch size, about 5.8 x 4.0 x 1.0 inches (14.7 x 10.2 x 2.5 cm) and 1.2 lb (about 0.54 kg).

How long 4TB lasts depends on the number of cameras, their resolution and bit rate, the compression format, and whether the system records continuously or only on motion. Many recorders show a retention estimate once you enter those settings.

Workload figure and bay support

Western Digital lists a workload rate of up to 180 TB per year. Workload rate is the amount of data written to or read from the drive, scaled to a full year. The brand notes that it varies with your hardware, software and configuration. Surveillance drives are designed for a high, steady write load, so this figure matters more here than it would for a drive that mostly sits idle.

The listing also states support for up to 16 bays for drives of 3TB and above (1TB to 2TB drives support up to eight). That tells you the drive is intended for multi-drive recorders, not only single-bay boxes. Components on 3TB and larger capacities are described as tarnish-resistant.

Compatibility

Western Digital says the drive is tested for compatibility with a wide range of security systems. Even so, recorders differ in which drive capacities and models they accept, so the recorder manufacturer's list is the final word.

Who it suits

It suits home and small-business security systems that record continuously and need a replacement or an additional drive for an NVR or DVR. It is less suited to uses it wasn't designed for, such as a general-purpose desktop boot drive.

What to check before you buy

• Recorder compatibility: confirm your NVR or DVR supports 3.5-inch SATA drives of this capacity.
• Storage needed: estimate days of footage from your camera count, resolution and recording mode.
• Bay count: check how many drives your recorder holds and whether mixing capacities is allowed.
• Existing drives: some recorders need drives to be formatted or added in a particular order.
• Mounting: check the screws, trays and cables your recorder needs, as the drive is sold on its own.

The short version

• A 4TB, 3.5-inch SATA 6 Gb/s internal drive with a 256 MB cache.
• Built for 24/7 surveillance recording, with AllFrame firmware tuning for many video streams.
• Listed workload rate of up to 180 TB per year; supports up to 16 bays at this capacity.
• Sold for use in recorders, so check your recorder's compatibility list first.

Bloiq is reader-supported. Some links may earn us a commission; it never affects what we write. How we make money.