Earlier this year, Western Digital introduced its Ultrastar DC SN861 SSDs, sparking curiosity about the controller behind these drives. Initially, the company kept this detail under wraps, leading many to assume it was their own creation. However, a recent teardown revealed that Western Digital opted for a controller from Fadu, a South Korean company established in 2015, known for its enterprise-grade SSD solutions.
The Ultrastar DC SN861 is designed for hyperscale datacenters and enterprises hungry for high performance, particularly with the current shift to PCIe Gen5 storage devices. A detailed look from a Storage Review article uncovered that this SSD is powered by Fadu’s FC5161 controller, which is NVMe 2.0-compliant. This controller is noteworthy for its 16 NAND channels that operate with an ONFi 5.0 2400 MT/s interface. It brings a host of advanced features like OCP Cloud Spec 2.0, SR-IOV, up to 512 namespaces for ZNS, flexible data placement, NVMe-MI 1.2, as well as robust security and telemetry capabilities. These are not typically available on other standard controllers or even previous Western Digital innovations.
The performance stats are quite impressive: the Ultrastar DC SN861 delivers sequential read speeds reaching 13.7 GB/s and sequential write speeds up to 7.5 GB/s. When it comes to random performance, it reaches up to 3.3 million random 4K read IOPS and 0.8 million random 4K write IOPS. The SSDs come in a range of capacities from 1.6 TB to 7.68 TB, supporting endurance ratings of one or three drive writes per day over five years. They are available in U.2 and E1.S form factors.
These two form factors cater to different needs: the E1.S model is tailored for cloud environments, featuring FDP and performance boosts, while the U.2 version is optimized for high-performance enterprise tasks and new applications such as AI.
Beyond its impressive specs, the Ultrastar DC SN861 stands out for its energy efficiency, boasting a 5W idle power consumption. This might seem like a small improvement over the previous SN840’s 6W, but when you’re running thousands of drives, every watt plays a crucial role in total cost of ownership.
Currently, Western Digital’s Ultrastar DC SN861 SSDs are available to selected clients, including big names like Meta, and interested buyers. Pricing details remain under wraps for now and are expected to vary based on purchase volumes.
Sources: Fadu, Storage Review.
