WD121KFBX

The WD121KFBX is a 3.5-inch SATA hard drive in Western Digital’s WD Red Pro NAS hard-drive line, with a formatted capacity of 12TB, a 7200 RPM spindle speed, 256 MB of cache and Helium drive technology, recording with CMR over a SATA interface rated at 6Gb/s.

Key figures

• Formatted capacity: 12TB.
• Form factor: 3.5-inch; interface: SATA, 6Gb/s.
• Spindle speed: 7200 RPM; cache: 256 MB; recording technology: CMR.
• Drive technology: Helium.
• Workload rate up to 550 TB per year; operating temperature 0°C to 65°C; projected MTBF 2,000,000 hours.

What this document does and does not state

WD121KFBX is a single orderable part number within the WD Red Pro family. The data sheet lists several WD Red Pro 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 five 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 Pro NAS Hard Drive — Western Digital Data Sheet (©2025 Western Digital Corporation), md5 0b0074348e7103ecf99348a63711778d. 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 WD121KFBX 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.