NVMe v1.4 spec がでたとのこと。Latest spec は
こちらから。
もとの記事にもあるけど、個人的に注目なのは PMR とCMB(こちらは一応v1.2/1.3でも記載はある)。
The 1.2 spec introduced the Controller Memory Buffer, which makes some of the SSD's DRAM directly accessible through PCI address space. This allows the IO command submission and completion queues to live in the SSD's memory instead of the host CPU's memory, which can reduce latency on the submission side, and can cut out some unnecessary copying in NVMe over Fabrics situations where peer to peer DMA between the SSD and the network card allows data to bypass the host DRAM entirely. The new Persistent Memory Region (PMR) feature in NVMe 1.4 operates similarly—the host system can read or write to this memory directly using basic PCIe transfers, without any of the overhead of command queues. In practice a Controller Memory Buffer is usually intended to be used in support of normal NVMe operation, but a PMR won't be involved in any of that.
あとは、コンシステンシー保証をどうするかか。