NVM Express

NVM Express
Non-Volatile Memory Host Controller Interface Specification
AbbreviationNVMe
StatusPublished
Year started2011 (2011)
Latest version2.1
August 5, 2024[1]
OrganizationNVM Express, Inc. (since 2014)
NVM Express Work Group (before 2014)
Websitenvmexpress.org

NVM Express (NVMe) or Non-Volatile Memory Host Controller Interface Specification (NVMHCIS) is an open, logical-device interface specification for accessing a computer's non-volatile storage media usually attached via the PCI Express bus. The initial NVM stands for non-volatile memory, which is often NAND flash memory that comes in several physical form factors, including solid-state drives (SSDs), PCIe add-in cards, and M.2 cards, the successor to mSATA cards. NVM Express, as a logical-device interface, has been designed to capitalize on the low latency and internal parallelism of solid-state storage devices.[2]

Architecturally, the logic for NVMe is physically stored within and executed by the NVMe controller chip that is physically co-located with the storage media, usually an SSD. Version changes for NVMe, e.g., 1.3 to 1.4, are incorporated within the storage media, and do not affect PCIe-compatible components such as motherboards and CPUs.[3]

By its design, NVM Express allows host hardware and software to fully exploit the levels of parallelism possible in modern SSDs. As a result, NVM Express reduces I/O overhead and brings various performance improvements relative to previous logical-device interfaces, including multiple long command queues, and reduced latency. The previous interface protocols like AHCI were developed for use with far slower hard disk drives (HDD) where a very lengthy delay (relative to CPU operations) exists between a request and data transfer, where data speeds are much slower than RAM speeds, and where disk rotation and seek time give rise to further optimization requirements.

NVM Express devices are chiefly available in the form of standard-sized PCI Express expansion cards[4] and as 2.5-inch form-factor devices that provide a four-lane PCI Express interface through the U.2 connector (formerly known as SFF-8639).[5][6] Storage devices using SATA Express and the M.2 specification which support NVM Express as the logical-device interface are a popular use-case for NVMe and have become the dominant form of solid-state storage for servers, desktops, and laptops alike.[7][8]

  1. ^ Cite error: The named reference v21 was invoked but never defined (see the help page).
  2. ^ "NVM Express". NVM Express, Inc. Retrieved 2017-01-24. NVMe is designed from the ground up to deliver high bandwidth and low latency storage access for current and future NVM technologies.
  3. ^ Tallis, Billy (June 14, 2019). "NVMe 1.4 Specification Published: Further Optimizing Performance and Reliability". AnandTech. Archived from the original on 2021-01-27.
  4. ^ Drew Riley (2014-08-13). "Intel SSD DC P3700 800GB and 1.6TB Review: The Future of Storage". Tom's Hardware. Retrieved 2014-11-21.
  5. ^ "Intel Solid-State Drive DC P3600 Series" (PDF). Intel. 2015. pp. 18, 20–22. Archived from the original (PDF) on Oct 28, 2015. Retrieved 2015-04-11.
  6. ^ Paul Alcorn (2015-06-05). "SFFWG Renames PCIe SSD SFF-8639 Connector To U.2". Tom's Hardware. Retrieved 2015-06-09.
  7. ^ Cite error: The named reference ahci-nvme was invoked but never defined (see the help page).
  8. ^ Paul Wassenberg (2013-06-25). "SATA Express: PCIe Client Storage" (PDF). SATA-IO. Archived from the original (PDF) on 2013-10-04. Retrieved 2014-11-21.

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