HDDs of the future: hard drives should get PCIe and NVMe


pcie nvme
OCP Virtual Summit
At the OCP Virtual Summit, there was once more talk about changing the interfaces of hard drives (HDD). As with Ssds, the transition from SATA to PCI Express and Nvme is being considered and with SATA Express a first step in this direction had failed.

Microsoft architect sees the future in Nvme Hdds



Jason Adrian, the Storage Hardware Architect for the cloud provider Microsoft Azure, sees Nvme Hdds as the future. Since the switch to the Pcie interface and the Nvme protocol for other mass storage devices such as Ssds is already underway, Adrian sees this as a logical step for Hdds. In his presentation, he describes Pcie as a native interface to the CPU. A protocol translation of AHCI at SATA-Hdds would be eliminated by the change. Server Ssds could be connected directly to the CPU via Pcie and would not have to go the way via a controller for the SAS interface. In addition, uniform drivers for systems with a combination of Hdds and Ssds could be used in the future.

Pcie delivers enough power



For the performance of current hard drives, a single Pcie lane is sufficient, which allows up to 985 MB/s (gross) in revision Pcie 3.0. The throughput rate is also sufficient for the expected multi-actuator Hdds: Seagate has promised a maximum of 520 MB/s for the Mach.2 technology, which is used in enterprise hard drives of the Exos series and is also being considered for Microsoft Azure. If dual porting is required, two Pcie-x1 lanes would have to be used.

OCP Summit 2020: Nvme Hdds


Unlike SSDs, however, SATA and SAS do not yet reach their performance limits with Hdds, which means that there is no immediate need to change the interface. Nevertheless, Adrian appeals to the industry with the above-mentioned arguments to lay the foundation for change plans in 2025 and thereafter.

SATA Express had failed



However, it would not be the first attempt in this direction, because a few years ago, SATA Express took a step towards hard drives with Pcie connectivity, which was primarily intended for hybrid hard drives with fast flash memory and Ssds. But the wedding of SATA protocol and Pcie interface did not prevail and the project SATA Express came to a standstill.

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