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Silver 3.5 inch bare SATA hard drive, rectangular metal casing, label on side

Western Digital

Western Digital WD40PURZ 4TB 5400 RPM 64MB Cache 3.5" SATA internal hard drive

SKU CH-XJ0V-2138D MPN WD40PURZ

A 4TB 3.5" SATA drive built for 24/7 surveillance workloads with 64MB cache and 5400 RPM operation

  • Total capacity4 TB
  • Interface typeSATA 6.0Gb/s
  • Form factor3.5 in (8.89 cm)
  • Packaging typeBare Drive
  • Flash memory typeHard Drive
  • Rotational speed5,400 RPM
  • Engineered for 24/7 surveillance workloads
  • Supports up to 180TB per year workload rate
  • 64MB cache optimises write-intensive streaming
  • Tarnish-resistant components withstand NVR heat and vibration
  • 5-inch SATA 6.0Gb/s interface fits standard bays

WD Purple 4TB surveillance drive

The WD Purple WD40PURZ is a 4TB 3.5-inch internal hard drive engineered for 24/7 video surveillance workloads. It connects via SATA 6.0Gb/s and is tuned for write-intensive, low bit-rate, high stream-count applications typical of NVR environments. The drive is tested for compatibility across a wide range of security systems. It is not suited for general desktop storage or workloads that demand low-latency random access.

Thermals, noise and power

Designed to withstand elevated heat fluctuations and equipment vibrations inside always-on NVR enclosures. The 5400 RPM spindle speed and surveillance-class firmware help manage thermal output during continuous write operations. Exclusive AllFrame technology reduces frame loss and improves video playback smoothness. Tarnish-resistant components add durability in harsh operating conditions.

180TB annual workload rating

The drive supports up to 180TB per year workload rate, a figure that determines whether it matches the write volume of your surveillance deployment. It also supports installations of more than 8 bays and includes TLER and ATA streaming support. Buyers needing higher capacity can choose models up to 18TB. Builders requiring a drive optimised for random read performance or desktop operating systems should select a different product class.

How it compares

Measured against everything we stock in 3.5-Inch Internal Desktop HDDs, at today’s prices. Recalculated every night.

Price $83.99
Cheaper than about 58% of the 4,938 comparable items (median $107.99).
Total capacity 4 TB
Higher than about 70% of the 2,372 comparable items (median 2 TB).
Price per TB $21.00 per TB
Cheaper than about 92% of the 2,365 comparable items (median $62.21 per TB).

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Specifications

Product
Brand nameWD
Product linePurple
Model nameWD40PURZ
Total capacity4 TB
Recommended useFor Video Surveillance
Performance
Rotational speed5,400 RPM
Storage
Flash memory typeHard Drive
Cache memory64 MB
Ports & slots
Interface typeSATA 6.0Gb/s
Size & build
Form factor3.5 in (8.89 cm)
Max height26.1 mm
Maximum width101.6 mm
Maximum length147 mm
Shipping weight0.79 kg
Package size210 × 156 × 114 mm

Questions about this item

How do I install the 3.5" WD Purple drive in my NVR and which step do people most often miss?

Mount the drive using the 3.5" screw holes, connect the SATA 6.0Gb/s data cable and the SATA power connector, then enable TLER or ATA streaming in the NVR BIOS — that last setting is the one installers forget.

What maintenance or replacement will the WD40PURZ need after long-term 24/7 recording?

The drive is rated for a 180TB/year workload; once cumulative writes approach that annual limit you should plan a proactive swap to avoid unexpected downtime.

What is the first limit that appears when the 5400 RPM drive runs sustained multi-stream writes?

The 64MB cache and 5400 RPM spindle set the sustained write ceiling; under heavy stream counts you hit throughput saturation before thermal throttling becomes an issue.

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