Non-volatile memory (NVM) or non-volatile storage also called long-term storage, persistent storage, or permanent storage is a type of computer memory that can retain the stored information even after power is removed. In contrast, volatile memory needs constant power in order to retain data. Three common examples of NVS devices that persistently store data are tape drives, HDDs, and SSDs. The term non-volatile storage also applies to the semiconductor chips that store data or controller program code within devices such as SSDs, HDDs, tape drives, and memory modules.
Non-volatile memory is a very advanced storage technology. It does not use continuous power to keep the data or program files located on the computer so that it becomes an effective power saver.
System manufacturers make a variety of non-volatile memory chips for various purposes. For example, non-volatile memory can store controller program code for devices, such as hard disk drives (HDD) and disk tapes. Other types of non-volatile memory (NVM) are commonly used to save data in USB storage, solid-state drives (SSD) or devices such as memory cards and smartphones, etc.
Solid-state storage usually uses a non-volatile memory type known as Flash memory. SSDs do not have moving components and are capable of output higher than HDDs and tape that use ahead to read and write data to magnetic storage media. SSDs directly connected to a device’s processor through a PCI Express bus that provides lower latency than Serial-Attached SCSI or Serial Advanced Technology Adapter-based SSDs attached to an external disc.
Types of non-volatile memory
Many other NVM memory types are widely used to read and write data to and from business and personal devices; each has its own advantages and disadvantages. NAND flash, the most common type used in data storage, includes several variants, such as single-level cells or one bit per multi-level cell or two bits per cell; three-level cells or three bits per cell and quad-level cells or four bits per cell, respectively
Manufacturers kept updating NAND flash technology to reduce cost per bit. When they had difficulty in scaling two-dimensional NAND technology, which has a single layer of memory cells, they introduced 3D NAND flash memory.
Technology vendors are also continuing to work on additional NVMe technologies to minimize costs, enhance efficiency, improve data storage capacity, and decrease energy usage.
What is the difference between non-volatile and volatile memory?
Volatile memory is a semiconductor technology that requires a continuous power supply to maintain stored data. Static and dynamic random-access memory are common examples of transient memory. Manufacturers also augment volatile memory devices with battery power to support continuous data storage.
Computer systems of companies and clients also use a mix of volatile and non-volatile memory technology, and each form of memory has its own strengths and weaknesses.
SRAM, for example, is faster than DRAM, which is better suited for the high-speed cache. DRAM, a successor to SRAM, is cheaper to make and consumes less power than SRAM when it is in the active mode.
The non-volatile NAND flash memory is slow to write and read data than the DRAM and SRAM. NAND flash, however, is less costly than DRAM and SRAM to manufacture. It makes the technology a perfect pairing for persistent data storage in smartphones and enterprise systems.
NVM vs. NVMe
The words non-volatile memory and non-volatile memory express are similar-sounding, but they are distinct and have special features. NVM is a semiconductor-based technology developed in the 1950s, while NVMe is a host controller platform and storage protocol created by a technology providers partnership in 2009.
On 1 March 2011, the NVM Host Controller Interface Work Group released the 1.0 NVMe specification. NVMe is designed to accelerate data transmission between host systems and SSDs via the PCIe bus on a device. NVMe supports various non-volatile memory types, such as the NAND flash and the Intel and Micron 3D XPoint technology.
NVMe is an alternative to the conventional Compact computer system Interface and Advanced Technology Connection in use with SAS and SATA drives. Compared to the SCSI and ATA command sets, non-volatile memory requires less than half the processing instructions. Non-volatile (NVM) based PCIe SSDs have lower latency, greater IOPS and significantly consume less power relative to SAS and SATA-based SSDs.
