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A Non-Volatile Dual In-line Memory Module (NVDIMM) is a computer memory DRAM DIMM that retains data even when electrical power is removed either from an unexpected power loss, system crash or from a normal system shutdown. NVDIMMs can be used to improve application performance, data security, system crash recovery time and to enhance SSD endurance and reliability.
NVDIMMs have evolved from the BBU (Battery Backed Up) DIMM which used a backup battery to sustain power to the volatile DIMM for up to 72 hours; now, to a complete subsystem that includes multiple memory technologies and uses supercapacitors as a power source. The BBU DIMM was originally designed for RAID HBAs (Host Bus Adaptors) or systems in order to preserve the contents of the volatile DRAM memory used for cache. However, in computer based applications, batteries have several maintenance and environmental concerns because of their limited life span and hazardous disposal. Furthermore, batteries contain heavy metals which violate RoHS compliance. The NVDIMM were conceived to eliminate the problems associated with batteries in BBU DRAM memory modules. As of November 2012, most NVDIMMs use NAND FLASH to preserve data, and have moved beyond RAID applications into fast storage appliances or in-memory processing for the data center and cloud computing.
Over the last two decades, numerous memory technologies have been brought to market such as Static RAM (SRAM), Pseudo Static RAM, NOR Flash, Eprom, EEprom, DRAM and NAND flash. The NVDIMM is a mixed memory subsystem that combines the speed and endurance of DRAM, together with the non-volatile data retention properties of NAND flash. NVDIMMs using DRAM and NAND technology can deliver high speed and low latency "non-volatile/persistent" memory with unlimited read/write activity that can sustain itself from host power failure or a system crash.
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NVDIMMs are now available with DDR3 DRAM technology, followed by DDR4 based solutions that are intended for integration with the next generation release of Intel CPU, Haswell. There are new non-volatile memory technologies that are currently in development, including MRAM, ReRAM, phase-change memory and racetrack memory, however, many believe[who?] it unlikely for any of these new technologies to be commercially viable for mainstream server adoption until the end of the decade. Mobile computing and the internet are pushing more demand for cloud based activity. Disk-based storage is becoming increasingly problematic in meeting the needs of large-scale cloud applications. Recently introduced RAM-based storage is being proposed by aggregating the RAM of thousands of commodity servers in data center networks (DCN). NVDIMMs may increase in demand for this application.
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