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A Non-Volatile Dual In-line Memory Module (NVDIMM) is a computer memory RAM 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,〔(【引用サイトリンク】title=Whole-system Persistence with Non-volatile Memories )〕 data security, system crash recovery time and to enhance SSD endurance and reliability.〔(【引用サイトリンク】title=The Bleak Future of NAND Flash Memory )〕 There are two main types of NVDIMM cards: NVDIMM-F and NVDIMM-N. NVDIMM-F is a Flash device that resides on the memory interconnect. It is typically accessed via a block driver and has NAND Flash attributes such as high capacity, but slow access times (when missing the small front-end cache) NVDIMM-N is a byte-addressable memory-mapped device, which is typically accessed at memory or near-memory speeds. DDR4 NVDIMM-N cards are being sold by multiple hardware vendors and support is getting wider.〔(【引用サイトリンク】title=Welcome to the era of NVDIMM Cards )〕 ==History== 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 adapters) 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 was 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,〔http://www.storage-switzerland.com/Blog/Entries/2012/10/2_Does_DRAM_Storage_Still_Make_Sense.html〕 and have moved beyond RAID applications into fast storage appliances or in-memory processing for the data center and cloud computing. DDR3 NVDIMM cards are supported by few server vendors (e.g. Supermicro), but most of the standardization effort in 2014 and 2015 is focused on DDR4-based system. Such standardization efforts include JEDEC and ACPI. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「NVDIMM」の詳細全文を読む スポンサード リンク
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