Seagate has produced an NVMe-accessed bunch of disk drives at the Open Compute Summit, with a 2U JBOD (Just a Bunch of Disks) enclosure housing 12x 3.5-inch disk drives and accessed through an onboard PCIe 3 switch.
NVMe (Non-Volatile Memory Express) is a parallel access protocol for flash (non-volatile) storage, whereas hard disk drives (HDD), with one or latterly two read-write head actuators, have traditionally been accessed by serial protocols such as SAS and SATA, which are much slower. But, even so, the the NVM Express organisation released the NVMe v2.0 spec in June this year, broadening NVMe’s scope to cover enterprise and client SSDs, removable cards, compute accelerators and HDDs.
Seagate announced its NVMe-accessed HDDs in a blog, writing: “The implementation provides integrated NVMe protocol support within the HDD controller itself and requires no bridge. The goal is to pave the way for a seamless consolidated NVMe interface across HDDs and SSDs.“
In its view this will support streamlined storage composability, reduced total cost of ownership (TCO); energy savings; streamlined feature development, performance enhancements, minimised components required for infrastructure systems; easier and more flexible scaling; and the removal of proprietary code.
The Seagate demonstration system used ports with a native NVMe SoC featuring tri-mode transceivers supporting SAS, SATA and NVMe. It included support for multi-actuator hard drives, which Seagate has been developing (MACH.2), and SNIA Redfish management APIs. A phase two system will add PCIe 4 support and an NVMe-oF x16 RNIC (RDMA Network Interface Card).
Seagate told us: “Engineering demo units of the HDDs with NVMe will be sent to key customers by September 2022. By the middle of 2024, Seagate will ship customer demo units.” That’s 30 months away and today’s Seagate drives may well have given way to 30TB HAMR drives by then. A 12-slot NVMe JBOD containing a dozen of those in multi-actuator form would have 360TB of capacity and possibly 24 or even more actuators. That would help to keep its PCIe lanes busy.
We ask ourselves if Toshiba and Western Digital have similar NVMe HDD systems in their R&D labs, and expect they do.