NVDIMM

A NVDIMM (pronounced "en-vee-dimm") or non-volatile DIMM is a type of non-volatile memory (NVM) for computers using widely used DIMM form-factors. NVM is a memory that retains its contents even when electrical power is removed, for example from an unexpected power loss, system crash, or normal shutdown. NVDIMMs share the existing memory interconnect with ordinary DRAM DIMMs. Some of them (NVDIMM-N) act like ordinary DIMMs with added non-volatile functionality, allowing improvement of system crash recovery time. Others (NVDIMM-F) act more like a faster way to attach a solid-state drive (SSD), improving application performance.

NVDIMM-N products act very similarly to regular volatile memory. They use volatile memory during normal operation and dump the contents into non-volatile memory if the power fails, using an on-board backup power source. Volatile memory is faster than non-volatile; it is byte-addressable; and it can be written to arbitrarily, without concerns about wear and device lifespan. However, including a second memory to achieve non-volatility (and the on-board backup power source) increases the product cost compared to volatile memory.

There was a lot of interest in the early 2010s for the replacement of the NAND flash technology used in SSDs, as 2D NAND scaling came to a halt. The promise of new and faster nonvolatile memory technologies, nearly as cheap as NAND flash and as fast as DRAM, lead to a goal (in 2014) to scale cost-effectively scale out so persistent memory could replace DRAM as the main system memory in enterprise systems. This did not happen: the largest of these ventures, Intel's 3D XPoint memory, was offered as a DIMM in 2019–2022, but poor market reception ultimately lead to the cancellation of the department.

Nevertheless, hope remains for new non-volatile memory technologies. Magnetoresistive RAM continues to see use. A Nano-RAM based on carbon nanotubes was announced in 2020.