NAS Hard Drive
Western Digital WD Purple 4 TB (WD43PURZ)
The Western Digital WD Purple WD43PURZ is a 4 TB NAS-class hard drive aimed at Surveillance, Home. It spins at 5400 RPM with 256 MB of cache and carries a 3-year warranty. On this page you get the complete manufacturer specification, what the drive delivers inside common RAID levels, its measured or rated reliability, and where to buy it — all cross-checked against the datasheet.
| Capacity | 4 TB |
| Rotational speed | 5400 RPM |
| Cache | 256 MB |
| Interface | SATA 6Gb/s |
| MTBF | 1.0M h |
| URE rating | 1 / 1014 |
| Power (idle / load) | 3.3 / 4.0 W |
| Noise (idle / seek) | 23 / 25 dB |
| Workload rating | 180 TB/yr |
| Warranty | 3 years |
| Use cases | SurveillanceHome |
Four of these 4 TB drives in RAID 5 give you 12 TB usable and survive one failure; in RAID 6, 8 TB and two failures. Plug your exact drive count and RAID level into the calculator to see usable capacity, efficiency and rebuild risk.
Open in the RAID calculator →This model is not yet in the Backblaze Drive Stats public dataset, so no independent field failure rate is available. The manufacturer specifies an MTBF of 1.0M h and a 180 TB/yr workload rating — both signals that it is built for the sustained duty of a NAS rather than a desktop.
Is the Western Digital WD Purple 4 TB a good NAS drive?
Yes — it is a 5400 RPM NAS-class drive rated for 180 TB/yr of writes per year with a 3-year warranty, which puts it firmly in NAS-duty territory rather than desktop use. Suitability depends on your bay count and RAID level; use the RAID calculator to check usable capacity and rebuild risk for your setup.
How much usable space do I get from 4 TB drives in RAID 5?
With four 4 TB drives, RAID 5 yields 12 TB usable (capacity of three drives) and survives one failure; RAID 6 yields 8 TB and survives two. More drives raise both the usable total and the rebuild risk — the calculator computes the exact figures for any count.
What is the failure rate of the Western Digital WD Purple 4 TB?
This model is not yet in the public Backblaze Drive Stats dataset, so no independent field AFR exists. The manufacturer rates it at an MTBF of 1.0M h and 180 TB/yr annual workload — both NAS-grade figures.