NVMe Zoned Namespaces (ZNS) Command Set Specification

Command Set

The individual command set specifications allow NVM Express to isolate and independently evolve command sets for emerging technologies such as Zoned Namespaces, Key Value and eventually computational storage. The NVMe specifications before NVMe 2.0 included all command set details. NVMe 2.0 separates these command sets into different specifications.

The NVMe Base specification defines the Admin Command Set, which provides essential administrative and management commands, including identify and get-log-page.

What is the Zoned Namespaces (ZNS) Command Set specification?

The NVMe Zoned Namespaces (ZNS) interface is a command set developed by NVM Express. By dividing an NVMe namespace into zones, which are required to be sequentially written, ZNS offers essential benefits to hyper-scale organizations, all-flash array vendors and large storage-system vendors to take advantage of storage devices optimized for sequential write workloads. ZNS reduces device-side write amplification, over-provisioning and DRAM while improving tail latency, throughput and drive capacity. By bringing a zoned-block interface to NVMe SSDs, ZNS brings alignment with the ZAC/ZBC host model already being used by SMR HDDs and enables a zoned-block storage layer to emerge across the SSD/HDD ecosystem.

As of August 2024, NVMe is a set of the following eleven specifications:

  • NVM Express® Base Specification, Revision 2.1
  • Command Set Specifications:
    • NVM Express® NVM Command Set Specification, Revision 1.1
    • NVM Express® NVMe Zoned Namespaces Command Set Specification, Revision 1.2
    • NVM Express® Key Value Command Set Specification, Revision 1.1
    • NVM Express® Subsystem Local Memory Command Set Specification, Revision 1.0
    • NVM Express® Computational Programs Command Set Specification, Revision 1.0
  • Transport Specifications:
    • NVM Express® NVMe over PCIe Transport Specification, Revision 1.1
    • NVM Express® RDMA Transport Specification, Revision 1.1
    • NVM Express® TCP Transport Specification, Revision 1.1
  • NVM Express® NVM Express Management Interface Specification, Revision 2.0
  • NVM Express® NVMe Boot Specification, Revision 1.1

The NVM Express® Base Specification, Revision 2.1 reorganizes sections to distinguish requirements on functionality common to PCIe® and Fabrics implementations, specific to PCIe implementations, and specific to Fabrics implementations.