Fadu’s FC5161 SSD Controller Unveiled in Western Digital’s PCIe Gen5 Enterprise Drives

Earlier this year, Western Digital unveiled their Ultrastar DC SN861 SSDs, but kept a tight lid on the specifics of the controller powering these new drives. This left many speculating that the company was using a proprietary controller. Recently, however, a teardown revealed a different story: it turns out Western Digital opted for a controller from Fadu, a South Korean enterprise specializing in top-tier SSD solutions since its founding in 2015.

The Ultrastar DC SN861 targets hyperscale data centers and enterprise clients demanding top-notch performance with their PCIe Gen5 storage devices. As revealed in a Storage Review article, this drive is equipped with Fadu’s FC5161 NVMe 2.0-compliant controller. The controller features 16 NAND channels supporting an ONFi 5.0 2400 MT/s interface. It brings high-end enterprise capabilities, including OCP Cloud Spec 2.0, SR-IOV, multiple namespaces for ZNS support, flexible data placement, NVMe-MI 1.2, and advanced security measures. It also provides telemetry and power loss protection, features that weren’t available on previous Western Digital controllers.

Performance-wise, the Ultrastar DC SN861 SSD impresses with sequential read speeds reaching up to 13.7 GB/s and sequential write speeds peaking at 7.5 GB/s. When it comes to random performance, it can handle up to 3.3 million random 4K read IOPS and up to 0.8 million random 4K write IOPS. Storage capacities range from 1.6 TB to 7.68 TB with endurance ratings of one or three drive writes per day over a five-year span, available in both U.2 and E1.S form factors.

Although the SN861 shares a similar design approach across its two form factors, Western Digital has tailored each to fit specific workloads. The E1.S variant is optimized for cloud environments with FDP and performance boosts, while the U.2 model focuses on high-powered enterprise tasks and new technologies such as AI.

This high-performance, enterprise-grade SSD sports a unique feature: its idle power consumption is just 5W—remarkably efficient for an enterprise drive and even 1W less than its predecessor, the SN840. For businesses deploying thousands of these drives, even such small energy savings can significantly impact total cost of ownership.

The Ultrastar DC SN861 SSDs are currently available to select clients, including major players like Meta. While pricing specifics remain undisclosed, they’ll likely vary depending on order volume and other factors.