Earlier this year, Western Digital launched its Ultrastar DC SN861 SSDs, keeping folks guessing about the controller it was using. At first, many thought the company had opted for an internally-developed piece. However, a recent teardown revealed a different story—Western Digital has partnered with Fadu, a South Korean enterprise renowned for its high-end SSD solutions since its inception in 2015.
Geared towards enterprise clients and demanding hyperscale datacenters transitioning to PCIe Gen5 storage, the Western Digital Ultrastar DC SN861 SSD features the FC5161 NVMe 2.0-compliant controller from Fadu. This powerhouse of a controller supports up to 16 NAND channels via an ONFi 5.0 2400 MT/s interface and is packed with advanced features like the OCP Cloud Spec 2.0, SR-IOV, ZNS support with up to 512 name spaces, flexible data placement, NVMe-MI 1.2, enhanced security measures, telemetry, and power loss protection. None of these capabilities are found in previous Western Digital controllers or other off-the-shelf options.
Performance-wise, the Ultrastar DC SN861 SSD impresses with sequential read speeds of up to 13.7 GB/s and write speeds peaking at 7.5 GB/s. It also delivers up to 3.3 million random 4K read IOPS and 0.8 million random 4K write IOPS. These SSDs are available in storage capacities ranging from 1.6 TB to 7.68 TB, with endurance ratings of one or three drive writes per day over a five-year span. They come in both U.2 and E1.S form factors.
The two designs, while technically similar, cater to different needs. The E1.S form factor boosts performance specifically for cloud environments with features like FDP, whereas the U.2 version targets high-performance enterprise tasks and emerging sectors such as AI.
Another standout aspect of the Ultrastar DC SN861 is its efficient power usage, drawing a mere 5W at idle. This is about 1W less compared to its predecessor, the SN840. In the realm of massive deployments where every watt affects total cost of ownership, these savings are noteworthy.
These high-performance Ultrastar DC SN861 SSDs are now available to select customers, including industry giants like Meta, though pricing details remain under wraps, influenced heavily by order volumes.
References: Fadu, Storage Review
