Earlier this year, Western Digital rolled out its Ultrastar DC SN861 SSDs, leaving many speculating about the controller inside. Initially, the specifics were under wraps, leading some to think Western Digital had crafted an in-house controller. However, a recent disassembly has clarified the mystery—it turns out the company opted for Fadu’s controller, a South Korean enterprise focused on high-performance SSD technology since its inception in 2015.
The Ultrastar DC SN861 SSD is engineered with performance-centric hyperscale data centers and enterprises in mind, which are increasingly embracing PCIe Gen5 storage solutions. A closer look from a Storage Review article reveals that the drive runs on Fadu’s FC5161, a controller compliant with NVMe 2.0 standards. This controller is equipped with 16 NAND channels supporting the ONFi 5.0 2400 MT/s interface and packages a host of enterprise-grade features such as OCP Cloud Spec 2.0, SR-IOV, support for up to 512 namespaces for ZNS, flexible data management, NVMe-MI 1.2, advanced security measures, telemetry, and power loss protection. These attributes outshine anything found on previous Western Digital controllers or typical off-the-shelf alternatives.
When it comes to performance, the Ultrastar DC SN861 doesn’t hold back. It delivers sequential read speeds of up to 13.7 GB/s and sequential write speeds reaching 7.5 GB/s. The drive also impresses with random performance figures of up to 3.3 million random 4K read IOPS and up to 0.8 million random 4K write IOPS. It comes in a variety of capacities ranging from 1.6 TB to 7.68 TB and offers one or three drive writes per day (DWPD) over five years. Additionally, it supports both U.2 and E1.S form factors.
Western Digital has tailored the two form factors for distinct needs: the E1.S variant is tuned for cloud environments, featuring FDP and performance optimization. In contrast, the U.2 model is designed for high-demand enterprise scenarios and cutting-edge applications like AI.
The Ultrastar DC SN861 stands out not only for its comprehensive feature set but also for its efficient use of power. It operates at just 5W during idle, which is notably lower than its predecessor, the SN840, by about 1W. For hyperscale operators, who run thousands of these drives, such energy efficiency can significantly impact total cost of ownership.
Currently, Western Digital’s Ultrastar DC SN861 SSDs are available to a select clientele, including big names like Meta, among others. Pricing remains undisclosed, largely influenced by purchase volumes and other factors.
Sources: Fadu, Storage Review
