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Silver 3.5 inch internal hard drive with exposed circuit board on underside

Western Digital

Western Digital WD121KFBX 12TB 7200 RPM 256MB SATA 3.5" internal hard drive

SKU CH-E7B8-WZTCH MPN WD121KFBX

A 12 TB, 7200 RPM SATA desktop drive with 256 MB cache, built for multi-bay NAS systems

  • InterfaceSATA 6.0Gb/s
  • Capacity12TB
  • NAND Flash Memory TypeHard Drive
  • RPM7200 RPM
  • Cache256MB
  • FeaturesAvailable in large capacities with support for 1-24 bays Enh
  • 12TB capacity for large NAS arrays
  • 7200 RPM spindle speed for fast data access
  • 256MB cache to accelerate read and write operations
  • Supports up to 24 drive bays for scalable storage
  • 300TB per year workload rating for heavy NAS use

12TB SATA NAS drive

The WD Red Pro WD121KFBX is a 12TB 3.5-inch internal hard drive built for multi-bay NAS enclosures. It spins at 7200 RPM with a 256MB cache and connects through a SATA 6.0Gb/s interface. The drive supports workloads up to 300TB per year and includes NASware 3.0 technology for error recovery control.

Built for 1–24 bay NAS, not single-drive desktops

This drive suits administrators who need high-capacity storage in RAID or JBOD arrays of up to 24 bays. Its vibration management and extended testing target continuous operation in NAS appliances. Builders wanting a quiet desktop drive or a boot device for a single-bay PC should look elsewhere.

Fits standard 3.5-inch bays with SATA power and data

The unit measures 147mm long, 101.6mm wide and 26.1mm high, matching common 3.5-inch drive trays. It requires a SATA data cable and a SATA power connector from the host system. The 6W operating draw leaves headroom for multiple drives on a single power supply rail.

Highlights

  • 12TB capacity for large NAS arrays
  • 7200 RPM spindle speed for fast data access
  • 256MB cache to accelerate read and write operations
  • Supports up to 24 drive bays for scalable storage
  • 300TB per year workload rating for heavy NAS use

Specifications

BrandWD
SeriesRed Pro
ModelWD121KFBX
InterfaceSATA 6.0Gb/s
Capacity12TB
NAND Flash Memory TypeHard Drive
RPM7200 RPM
Cache256MB
FeaturesAvailable in large capacities with support for 1-24 bays
Enhanced reliability with 3D Active Balance Plus technology and error recovery controls with NASware 3.0 technology
Extended drive testing to ensure each drive is tested for extended reliable operation
Vibration & Shock protection
UsageEnterprise NAS Hard Drives
Form Factor3.5"
Height (maximum)26.10mm
Width (maximum)101.60mm
Length (maximum)147.00mm
Shipping weight0.77 kg
Package size231 × 152 × 79 mm

Questions about this item

Does this 3.5" 12TB drive need a SATA power cable and a SATA data cable to operate?

Yes, the drive uses a standard SATA 6.0Gb/s interface and requires both a SATA data cable from the host and a SATA power connector from the power supply.

Can this 7200 RPM Red Pro drive share a NAS with slower existing drives?

The drive spins at 7200 RPM with a 256MB cache and supports up to 24 bays, so it can operate in the same enclosure as drives of different speeds.

How do I confirm the 12TB Red Pro is healthy after installation?

Check that the system BIOS or NAS OS detects the full 12TB capacity at SATA 6.0Gb/s, then run the built-in SMART self-test and verify zero reallocated sectors.

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