4 research outputs found
Algorithms and Data Representations for Emerging Non-Volatile Memories
The evolution of data storage technologies has been extraordinary. Hard disk drives
that fit in current personal computers have the capacity that requires tons of transistors
to achieve in 1970s. Today, we are at the beginning of the era of non-volatile memory
(NVM). NVMs provide excellent performance such as random access, high I/O speed, low
power consumption, and so on. The storage density of NVMs keeps increasing following
Moore’s law. However, higher storage density also brings significant data reliability issues.
When chip geometries scale down, memory cells (e.g. transistors) are aligned much closer
to each other, and noise in the devices will become no longer negligible. Consequently,
data will be more prone to errors and devices will have much shorter longevity.
This dissertation focuses on mitigating the reliability and the endurance issues for two
major NVMs, namely, NAND flash memory and phase-change memory (PCM). Our main
research tools include a set of coding techniques for the communication channels implied
by flash memory and PCM. To approach the problems, at bit level we design error
correcting codes tailored for the asymmetric errors in flash and PCM, we propose joint
coding scheme for endurance and reliability, error scrubbing methods for controlling storage
channel quality, and study codes that are inherently resisting to typical errors in flash
and PCM; at higher levels, we are interested in analyzing the structures and the meanings
of the stored data, and propose methods that pass such metadata to help further improve
the coding performance at bit level. The highlights of this dissertation include the first
set of write-once memory code constructions which correct a significant number of errors,
a practical framework which corrects errors utilizing the redundancies in texts, the first
report of the performance of polar codes for flash memories, and the emulation of rank
modulation codes in NAND flash chips
RAID Organizations for Improved Reliability and Performance: A Not Entirely Unbiased Tutorial (1st revision)
RAID proposal advocated replacing large disks with arrays of PC disks, but as
the capacity of small disks increased 100-fold in 1990s the production of large
disks was discontinued. Storage dependability is increased via replication or
erasure coding. Cloud storage providers store multiple copies of data obviating
for need for further redundancy. Varitaions of RAID based on local recovery
codes, partial MDS reduce recovery cost. NAND flash Solid State Disks - SSDs
have low latency and high bandwidth, are more reliable, consume less power and
have a lower TCO than Hard Disk Drives, which are more viable for hyperscalers.Comment: Submitted to ACM Computing Surveys. arXiv admin note: substantial
text overlap with arXiv:2306.0876
High-Density Solid-State Memory Devices and Technologies
This Special Issue aims to examine high-density solid-state memory devices and technologies from various standpoints in an attempt to foster their continuous success in the future. Considering that broadening of the range of applications will likely offer different types of solid-state memories their chance in the spotlight, the Special Issue is not focused on a specific storage solution but rather embraces all the most relevant solid-state memory devices and technologies currently on stage. Even the subjects dealt with in this Special Issue are widespread, ranging from process and design issues/innovations to the experimental and theoretical analysis of the operation and from the performance and reliability of memory devices and arrays to the exploitation of solid-state memories to pursue new computing paradigms