WD40EFPX

The WD40EFPX is a 3.5-inch SATA hard drive in Western Digital’s WD Red Plus NAS hard-drive line, with a formatted capacity of 4TB, running at 5400 RPM with 256MB of cache and Air drive technology, recording with CMR over a SATA 6 Gb/s interface.

Key figures

• Formatted capacity: 4TB.
• Form factor: 3.5-inch; interface: SATA 6 Gb/s.
• Spindle speed: 5400 RPM; cache: 256MB; recording technology: CMR.
• Drive technology: Air.
• Workload rate up to 180 TB per year; operating temperature 0 to 65°C; MTBF 1,000,000 hours.

What this document does and does not state

WD40EFPX is a single orderable part number within the WD Red Plus family. The data sheet lists several WD Red Plus capacities and model codes as separate orderable part numbers; the figures shown here are for this one code only. The data sheet prints a per-model Recording Technology row with CMR for this line and a Limited warranty row of three years, but it does not print a sector-format designation beyond “Advanced Format (AF): Yes”, so no 512e/512n claim is made. Sustained (internal) transfer rates are deliberately not asserted: the manufacturer’s own data-sheet and product-page figures disagree for some models. The data sheet publishes no temperature-grade or qualification standard and no lifecycle status for this line, so those are intentionally not asserted here.

Data source

Figures are taken from the manufacturer data sheet WD Red Plus NAS Hard Drive — Western Digital Data Sheet (©2025 Western Digital Corporation), md5 58b781ca0a7da06696dd0dd8a3135992. This is a manufacturer data-sheet copy, so no public datasheet link is claimed and the external reference points to the manufacturer product page at westerndigital.com.

Who makes it

The WD40EFPX is made by Western Digital Corporation, a United States–headquartered data storage company based in San Jose, California. © 2025 Western Digital Corporation or its affiliates.