NVDIMM

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A non-volatile dual in-line memory module (NVDIMM) is a type of random-access memory for computers. Non-volatile memory is memory that retains its contents even when electrical power is removed, for example from an unexpected power loss, system crash, or normal shutdown. "Dual in-line" identifies the memory as using the DIMM package. NVDIMMs improve application performance[1][not in citation given] and system crash recovery time. They enhance solid-state drive (SSD) endurance and reliability.[2][3]

"Non-volatile" products may 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.

Types[edit]

There are three types of NVDIMM implementations by JEDEC Standards org:[4][non-primary source needed]

  • NVDIMM-F: DIMM with flash storage. System users will need to pair the storage DIMM alongside a traditional DRAM DIMM. NVDIMM-F has been available since 2014.
  • NVDIMM-N DIMM with flash storage and traditional DRAM on the same module. The computer accesses the traditional DRAM directly. In the event of a power failure, the module copies the data from the volatile traditional DRAM to the persistent flash storage, and copies it back when power is restored. It uses a small backup power source for this.
  • NVDIMM-P specifications will be released by JEDEC around 2018[5] It will allow storage inside computer main memory, using ReRAM technology, and a DDR5 interface. A NVDIMM-P has persistent DRAM, and can access external block-oriented (flash memory) drive for memory cache.

Non-Standard NVDIMM implementations:

  • NVDIMM-X: DDR4 DIMM with NAND Flash storage and volatile DRAM on the same module, developed by Xitore.

As of November 2012, most NVDIMMs used NAND flash as the non-volatile memory.[6] Emerging memory technologies aim to achieve NVDIMM without a cache or two separate memories. Intel and Micron have announced use of the 3D XPoint PCM technology in NVDIMM-F.[7] Sony and Viking Technology have announced an NVDIMM-N product based on the ReRAM technology.[8] In 2015, Samsung and Netlist announced a NVDIMM-P product, possibly based on Z-nand.[9]

Backup power[edit]

NVDIMMs evolved from the BBU (battery backed up) DIMM, which used a backup battery to sustain power to a volatile memory for up to 72 hours. However, batteries are disfavored in computer components because they have a limited lifespan, they may be regarded as hazardous waste, and they contain heavy metals[citation needed] which violate RoHS compliance.

When the module includes non-volatile memory, backup power is required for only a short time after the computer's main power fails, while the module copies the data from volatile to non-volatile memory. Therefore, modern NVDIMMs use on-board supercapacitors to store energy.

Interface[edit]

A few server vendors, such as Supermicro, still make products using the DDR3 interface to the computer, but standardization work in 2014 and 2015, such as at JEDEC[10] and ACPI,[11] was based on the DDR4 interface.

Uses[edit]

The BBU DIMM was originally designed for use as the cache of RAID HBAs (host bus adapters) or systems, to enable data in the cache to survive a power failure. NVDIMMs have moved beyond RAID applications into fast storage appliances or in-memory processing for the data center and cloud computing.[12]

See also[edit]

References[edit]

  1. ^ Narayanan, Dushyanth; Hodson, Orion (March 2012). "Whole-system Persistence with Non-volatile Memories" (PDF). Microsoft Research. Archived (PDF) from the original on 2019-02-10. Retrieved 2014-05-08.
  2. ^ Grupp, Laura M.; Davis, John; Swanson, Steven (February 2012). "The Bleak Future of NAND Flash Memory" (PDF). Microsoft Research. Archived (PDF) from the original on 2019-02-10. Retrieved 2014-05-08.
  3. ^ Maleval, Jean Jacques (2013-03-11). "SSDs Risk Massive Data Loss". Storage Newsletter. Retrieved 2013-09-06. (Subscription required (help)).
  4. ^ Golander, Amit (2015-08-23). "Welcome to the era of NVDIMM Cards". Plexistor. Archived from the original on 2018-12-23. Retrieved 2015-08-23.
  5. ^ "JEDEC DDR5 & NVDIMM-P Standards Under Development". JEDEC. 2017-03-30. Archived from the original on 2018-06-16.
  6. ^ Crump, George (2012-10-02). "Does DRAM Storage Still Make Sense?". Storage Switzerland. Archived from the original on 2013-06-16.
  7. ^ Mah Ung, Gordon (2015-08-21). "Intels crazy fast 3D XPoint Optane memory heads for DDR slots but with a cache". PCWorld. Archived from the original on 2015-08-23. Retrieved 2015-08-21.
  8. ^ Russell, Gil (2015-08-11). "Viking technology and Sony in ReRAM memory mashup". TechEye. Archived from the original on 2016-04-16. Retrieved 2015-08-11.
  9. ^ Armstrong, Adam (2015-11-19). "Netlist And Samsung Partner To Deliver NVDIMM-P". Storage Review. Archived from the original on 2018-04-18.
  10. ^ "JEDEC announces support NVDIMM hybrid memory modules". JEDEC. 2015-05-26. Archived from the original on 2016-04-24. Retrieved 2015-05-26.
  11. ^ Larabel, Michael (2015-05-21). "ACPI 6 Non-Volatile Memory Device Support NFIT libND For Linux". Phoronix. Archived from the original on 2018-12-23. Retrieved 2015-05-21.
  12. ^ Verity, John W. (2012-09-19). "Non-Volatile DRAM Is Poised to Give Apps a Big Boost". Datacenter Acceleration. Archived from the original on 2013-06-16. Retrieved 2013-09-06.

External links[edit]