NVs

NVs, in a technology context, most often refer to non-volatile memories (NVMs)—a class of computer memory that retains stored data without power. They contrast with volatile memory, such as DRAM, which loses data when power is removed. NVs encompass a family of technologies with diverse characteristics, densities, and performance profiles. Common examples include flash memory (NAND and NOR), MRAM (magnetoresistive RAM), ReRAM (resistive RAM), FRAM (ferroelectric RAM), and PCM (phase-change memory). A related concept is storage-class memory, such as 3D XPoint (marketed as Optane), which aims to bridge the gap between traditional DRAM and NAND-based storage by offering persistence with memory-like latency.

Flash memory is the dominant NV technology in consumer and enterprise storage. It stores data in charge-trap or floating-gate structures and typically requires block-level erasure, influencing endurance and performance. MRAM offers byte-addressability, high endurance, and near-DRAM speeds in some variants, making it attractive for caches and embedded systems. ReRAM and PCM explore higher densities and potentially faster write times but face continued maturation and manufacturing challenges. FRAM emphasizes very high endurance and low power but lower density and cost considerations. Persistent-memory technologies like NVMe-based and byte-addressable NV memories enable software to treat non-volatile storage as part of the memory hierarchy, with operating systems and file systems evolving to support direct access to persistent memory.

In data centers and embedded devices, NVs are used to improve performance and resilience, enabling faster startup and data persistence across power cycles. Challenges include cost, endurance, and integration with existing software stacks, but industry research continues to advance density and reliability. NVs also denotes nitrogen-vacancy centers in diamond in quantum physics, defects used for high-sensitivity sensing and quantum information experiments.