Notes on Non-Volatile Memory

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NOTE These post series is merely a backup of some notes from my PhD sometime in 2016

Better Memory – Samuel Greengard, Communications of the ACM, 2016

  • Memristors rely on electrical resistance rather than electrical charge to encode a bit of information, increasing energy efficiency.
  • Enables perpetual computing devices — devices that compute if enough energy provided, or permanently store state otherwise.
  • HP — memristor
  • Intel & Micron — 3D XPoint

How Persistent Memory Will Change Software Systems – Anirudh Badam, IEEE, August 2013

  • Increased physical memory, persistence, data durability with low latency
  • “ensuring consistency will require more hardware and software support”
  • “the ability to make data durable at a low latency would help transactional aplications reduce data/work loss during crashes.
  • “Instant power-up and shutdown features”
  • “these systems will be able to readily repurpose their DRAM-based caches to work with the new technology, and nonvolatility would eliminate the need for a write-through to ensure data persistence”
  • “Although these systems can benefit from nonvolatility, they must avoid data persistence in an inconsistent state. In addition, to ensure persistent memory’s rapid adoption, applications that use these systems must continue to work with no or minimal modifications”
  • ” when updating the journal, the system could permanently move all writeahead logging and journaling of such file-system data to persistent memory”
  • In-memory databases! Persistent!
  • Moneta file system: “one [of the remaining open problems] is the need for some mechanism to provide safe, consistent, and efficient updates to file-system metadata — particularly for files shared across multiple applications”
  • In databases: “buffer caches based on persistent memory could support write transactions (with white-back support to disk) while providing ACID guarantees”
  • “data structures designed for DRAM have a high concurrency and finer-grained locking, making them more appropriate for new memory technologies than the ones designed for disks, which have a large seek latency and data locking at the block level.”

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