Dynamic Virtual Page-based Flash Translation Layer with Novel Hot Data Identification and Adaptive Parallelism Management

Solid-state disks (SSDs) tend to replace traditional motor-driven hard disks in high-end storage devices in past few decades. However, various inherent features, such as out-of-place update [resorting to garbage collection (GC)] and limited endurance (resorting to wear leveling), need to be reduced to a large extent before that day comes. Both the GC and wear leveling fundamentally depend on hot data identification (HDI). In this paper, we propose a hot data-aware flash translation layer architecture based on a dynamic virtual page (DVPFTL) so as to improve the performance and lifetime of NAND flash devices. First, we develop a generalized dual layer HDI (DL-HDI) framework, which is composed of a cold data pre-classifier and a hot data post-identifier. Those can efficiently follow the frequency and recency of information access. Then, we design an adaptive parallelism manager (APM) to assign the clustered data chunks to distinct resident blocks in the SSD so as to prolong its endurance. Finally, the experimental results from our realized SSD prototype indicate that the DVPFTL scheme has reliably improved the parallelizability and endurance of NAND flash devices with improved GC-costs, compared with related works.Peer reviewe

Self-Learning Hot Data Prediction: Where Echo State Network Meets NAND Flash Memories

© 2019 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising or promotional purposes, creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works.Well understanding the access behavior of hot data is significant for NAND flash memory due to its crucial impact on the efficiency of garbage collection (GC) and wear leveling (WL), which respectively dominate the performance and life span of SSD. Generally, both GC and WL rely greatly on the recognition accuracy of hot data identification (HDI). However, in this paper, the first time we propose a novel concept of hot data prediction (HDP), where the conventional HDI becomes unnecessary. First, we develop a hybrid optimized echo state network (HOESN), where sufficiently unbiased and continuously shrunk output weights are learnt by a sparse regression based on L2 and L1/2 regularization. Second, quantum-behaved particle swarm optimization (QPSO) is employed to compute reservoir parameters (i.e., global scaling factor, reservoir size, scaling coefficient and sparsity degree) for further improving prediction accuracy and reliability. Third, in the test on a chaotic benchmark (Rossler), the HOESN performs better than those of six recent state-of-the-art methods. Finally, simulation results about six typical metrics tested on five real disk workloads and on-chip experiment outcomes verified from an actual SSD prototype indicate that our HOESN-based HDP can reliably promote the access performance and endurance of NAND flash memories.Peer reviewe

Current, December 03, 1981

https://irl.umsl.edu/current1980s/1054/thumbnail.jp

November 30, 1989

The Breeze is the student newspaper of James Madison University in Harrisonburg, Virginia

September 7, 1979

The Breeze is the student newspaper of James Madison University in Harrisonburg, Virginia

Studies in Electrical Machines & Wind Turbines associated with developing Reliable Power Generation

The publications listed in date order in this document are offered for the Degree of Doctor of Science in Durham University and have been selected from the author’s full publication list. The papers in this thesis constitute a continuum of original work in fundamental and applied electrical science, spanning 30 years, deployed on real industrial problems, making a significant contribution to conventional and renewable energy power generation. This is the basis of a claim of high distinction, constituting an original and substantial contribution to engineering science

The 1982 NASA/ASEE Summer Faculty Fellowship Program

A NASA/ASEE Summer Faculty Fellowship Research Program was conducted to further the professional knowledge of qualified engineering and science faculty members, to stimulate an exchange of ideas between participants and NASA, to enrich and refresh the research and teaching activities of participants' institutions, and to contribute to the research objectives of the NASA Centers

Measurement of impact breakage properties of ore particles using a series of devices

Includes abstract.Includes bibliographical references (leaves 108-115).Single particle impact breakage experiments provide essential data to aid in the fundamental understanding of rock fracture in comminution. Such experiments, conducted using devices such as the drop weight tester, split Hopkinson bars and more recently the rotary breakage tester, have been successfully used to characterize ore breakage properties in relation to measured fracture energies. Current theoretical understanding of impact breakage is that there are three important energy regimes to the process. Below a certain energy value, Eo, breakage will never occur for an infinite number of impacts. Second is an intermediate energy zone for which breakage occurs after a number of consecutive impacts and after a critical energy value, Ecrit, is a regime where breakage typically occurs for a single impact. This work was therefore undertaken in order to identify the energy values described for impact breakage of a chosen homogenous ore and a conventional mining gold ore. Drop weight tests on gold ore were used to calculate A and b hardness parameters using both the standard JK breakage model and the modified Shi-Kojovic model. The A x b values with the modified model gave consistently higher values than the standard model, typically increasing by 2-5%. Split Hopkinson pressure bars were used to establish the ultimate compressive stress of blue stone through single impact breakage tests and the fraction of impact energy utilized to cause particle fracture. From these tests it was noted that less than 50% of available impact energy was utilized to cause fracture, with cylindrical specimens absorbing the highest fraction of 43%. The rotary breakage tester was used to conduct incremental breakage experiments with blue stone and gold ore. The probability to breakage at the impact energies tested was found to remain relatively consistent over consecutive impacts. This showed that a model could be fitted between the cumulative probability to breakage and the number of impacts at these energy levels. The values of Eo for blue stone and gold ore were calculated to be 0.0464 and 0.00366 respectively. Ecrit for 90% probability to first impact breakage for these two ores was 0.344 and 0.281 respectively. It was found that incremental breakage was much more inefficient than single impact breakage. From tests with both split Hopkinson pressure bars and the rotary breakage tester, breakage degrees for single impacts increased rapidly with increase in breakage energy whilst the breakage degrees obtained from incremental breakage tests for similar amounts of energy expended remained low

An Efficient FTL Design for Multi-Chipped Solid-State Drives

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