NVMe Polishes Its Specs, Brings Virtualization to Locally Attached SSDs

The latest NVMe specifications add SSD-level virtualization that can simplify live VM migration by preserving storage identities across servers. The updates also introduce support for post-quantum cryptography, controller-based rate limiting, voltage monitoring, and factory-reset capabilities. The Register reports: Announced by the NVM Express consortium, all 11 of the suite of NVMe specs have been updated with new features and engineering change notices. These represent the next step in the evolution of the standard, it says, which was created as a protocol to support storage devices connected to a system’s PCIe bus. Perhaps the most significant new capability is PCIe Exported NVM Subsystem Migration. This extends existing NVMe virtualization to locally-attached PCIe SSDs. It does this by abstracting the physical drives into host-defined virtualized NVM subsystems, to allow for virtual machine (VM) mobility without storage reconfiguration.

When a VM moves from one server to another, its storage also needs to move with it in a way that’s non-disruptive to any applications running in that VM. “With NVM Subsystem Migration, NVMe SSDs can present exported NVM subsystems that hide the complexity of the underlying hardware,” says Mike Allison, a senior director at SSD maker Samsung and NVM Express board member. “Instead of interacting with physical controllers and namespaces, the host only sees exported controllers and namespaces. This creates a clean separation between what the VM sees and what’s happening under the hood,” Allison explains on an NVM Express blog.

“One of the key innovations here is providing the host with control over exported identifiers. During migration, those identifiers can be carried over exactly from the source to the destination. That consistency is crucial: even if the underlying hardware uses different internal IDs, the VM sees no change and can pick up right where it left off with no storage reconfiguration required,” he says. In effect, the NVMe layer now enables the virtual machine manager (VMM) to rely on virtualization built into the SSD. The flash drive itself exposes logical, virtualized storage constructs, offloading this complexity from the VMM. You can learn more about the updated NVMe specifications here.