Stefan Mileschin

Western Digital is introducing a new high-end enterprise NVMe SSD, the Ultrastar DC SN840, and a NVMe over Fabrics 2U JBOF using up to 24 of these SSDs.

The Ultrastar DC SN840 uses the same 96L TLC and in-house SSD controller as the SN640, but the SN840 offers more features, performance and endurance to serve a higher market segment than the more mainstream SN640. The SN840 uses a 15mm thick U.2 form factor compared to 7mm U.2 (and M.2 and EDSFF options) for the SN640, which allows the SN840 to handle much higher power levels and to accommodate higher drive capacities in the U.2 form factor. The controller is still a PCIe 3 design so peak sequential read performance is barely faster than the SN640, but the rest of the performance metrics are much faster than the SN640: random reads now saturate the PCIe 3 x4 link and write performance is much higher across the board. Power consumption can reach 25W, but the SN840 provides a range of configurable power states to limit it to as little as 11W.

https://www.anandtech.com/show/15879...lport-nvme-ssd