The Western Digital SN850 is a solid-state drive in the M.2 2280 form factor, launched on October 8th, 2020. It is available in capacities ranging from 500 GB to 2 TB. This page reports specifications for the 1 TB variant. With the rest of the system, the Western Digital SN850 interfaces using a PCI-Express 4.0 x4 connection. The SSD controller is the Black G2 (20-82-10034-A1) Triton MP16+ from WD, a DRAM cache chip is available. Western Digital has installed 96-layer TLC NAND flash on the SN850, the flash chips are made by Toshiba. To improve write speeds, a pseudo-SLC cache is used, so bursts of incoming writes are handled more quickly. The cache is sized at 300 GB, once it is full, writes complete at 1340 MB/s. Thanks to support for the fast PCI-Express 4.0 interface, performance is excellent. The SN850 is rated for sequential read speeds of up to 7,000 MB/s and 5,300 MB/s write; random IO reaches 1000K IOPS for read and 720K for writes.
At its launch, the SSD was priced at 230 USD. The warranty length is set to five years, which is an excellent warranty period. Western Digital guarantees an endurance rating of 600 TBW, a typical value for consumer SSDs.