• Title/Summary/Keyword: flash storage

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Design and Test Flash-based Storage for Small Earth Observation Satellites (소형 지구 관측 위성용 플래시 기반 저장장치 설계 및 시험)

  • Baek, Inchul;Park, Hyoungsic;Hwang, Kiseon
    • IEMEK Journal of Embedded Systems and Applications
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    • v.13 no.5
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    • pp.253-259
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    • 2018
  • Recently, small satellite industries are rapidly changing. Demand for high performance small satellites is increasing with the expansion of Earth Observation Satellite market. A next-generation small satellites require a higher resolution image storage capacity than before. However, there is a problem that the HW configuration of the existing small satellite image storage device could not meet these requirements. The conventional data storing system uses SDRAM to store image data taken from satellites. When SDRAM is used in small satellite platform of a next generation, there is a problem that the cost of physical space is eight times higher and satellite price is two times higher than NAND Flash. Using the same satellite hardware configuration for next-generation satellites will increase the satellite volume to meet hardware requirements. Additional cost is required for structural design, environmental testing, and satellite launch due to increasing volume. Therefore, in order to construct a low-cost, high-efficiency system. This paper shows a next-generation solid state recorder unit (SSRU) using MRAM and NAND Flash instead of SDRAM. As a result of this research, next generation small satellite retain a storage size and weight and improves the data storage space by 15 times and the storage speed by 4.5 times compare to conventional design. Also reduced energy consumption by 96% compared to SDRAM based storage devices.

The Effect of Absorbing Hot Write References on FTLs for Flash Storage Supporting High Data Integrity (데이터 무결성을 보장하는 플래시 저장 장치에서 잦은 쓰기 참조 흡수가 플래시 변환 계층에 미치는 영향)

  • Shim, Myoung-Sub;Doh, In-Hwan;Moon, Young-Je;Lee, Hyo-J.;Choi, Jong-Moo;Lee, Dong-Hee;Noh, Sam-H.
    • Journal of KIISE:Computing Practices and Letters
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    • v.16 no.3
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    • pp.336-340
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    • 2010
  • Flash storages are prevalent as portable storage in computing systems. When we consider the detachability of Flash storage devices, data integrity becomes an important issue. To assure extreme data integrity, file systems synchronously write all file data to storage accompanying hot write references. In this study, we concentrate on the effect of hot write references on Flash storage, and we consider the effect of absorbing the hot write references via nonvolatile write cache on the performance of the FTL schemes in Flash storage. In 80 doing, we quantify the performance of typical FTL schemes for workloads that contain hot write references through a wide range of experiments on a real system environment. Through the results, we conclude that the impact of the underlying FTL schemes on the performance of Flash storage is dramatically reduced by absorbing the hot write references via nonvolatile write cache.

Flash Translation Layer for Heterogeneous NAND Flash-based Storage Devices Based on Access Patterns of Logical Blocks (논리 블록의 접근경향을 활용한 이종 낸드 플래시 기반 저장장치를 위한 Flash Translation Layer)

  • Bang, Kwanhu;Park, Sang-Hoon;Lee, Hyuk-Jun;Chung, Eui-Young
    • Journal of the Institute of Electronics and Information Engineers
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    • v.50 no.5
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    • pp.94-101
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    • 2013
  • The market for NAND flash-based storage devices has grown significantly as they rapidly replace traditional disk-based storage devices. Heterogeneous NAND flash-based storage devices using both multi-level cell (MLC) and single-level cell (SLC) NAND flash memories are also actively researched since both types of memories complement each other. Heterogeneous NAND flash-based storage devices suffer from the overheads incurred by migration from SLC to MLC and garbage collection of SLC. This paper proposes a new flash translation layer (FTL) for heterogeneous NAND flash-based storage devices to reduce the overheads by utilizing SLC efficiently. The proposed FTL analyzes the access patterns of logical blocks and selects and stores only logical blocks expected to bring performance improvement in SLC. The experimental results show that the total execution time of heterogeneous NAND flash-based storage devices with our proposed FTL scheme is 35% shorter than that with the previously proposed best FTL scheme.

FLASH : A Main Memory Storage System

  • Kim, Pyung-Chul;Jung, Byung-Gwan;Kim, Moon-Ja
    • The Journal of Information Technology and Database
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    • v.1 no.2
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    • pp.103-125
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    • 1994
  • In this paper, we introduce a new main memory storage system called FLASH that is designed for real-time applications. The FLASH system is characterized by the memory residency of data and a new fast and dynamic hashing scheme called extendible chained bucket hashing. We compared the performance of the new hashing algorithm with other well-known ones. Also, we carried out an experiment to compare the overall performance of the FLASH system with a commercial one. Both comparison results show that the new hashing scheme and the FLASH system outperforms other competitives.

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Regular File Access of Embedded System Using Flash Memory as a Storage (플래시 메모리를 저장매체로 사용하는 임베디드 시스템에서의 정규파일 접근)

  • 이은주;박현주
    • Journal of Information Technology Applications and Management
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    • v.11 no.1
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    • pp.189-200
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    • 2004
  • Recently Flash Memory which is small and low-powered is widely used as a storage of embedded system, because an embedded system requests portability and a fast response. To resolve a difference of access time between a storage and RAM, Linux is using disk caching which copies a part of file on disk into RAM. It is not also an exception on embedded system. A READ access-time of flash memory is similar to RAMs. So, when a process on an embedded system reads data, it is similar to the time to access cached data in RAM and to access directly data on a flash memory. On the embedded system using limited memory, using a disk cache is that wastes much time and memory spaces to manage it and can not reflects the characteristic of a flash memory. This paper proposes the regular file access of limited using a page cache in the file system based on a flash memory and reflects the characteristic of a flash memory. The proposed algorithm minimizes power consumption because access numbers of the RAM are reduced and doesn't waste a memory space because it accesses directly to a flash memory Therefore, the performance improvement of the system applying the proposed algorithm is expected.

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Cost-based Optimization of Block Recycling Scheme in NAND Flash Memory Based Storage System (NAND 플래시 메모리 저장 장치에서 블록 재활용 기법의 비용 기반 최적화)

  • Lee, Jong-Min;Kim, Sung-Hoon;Ahn, Seong-Jun;Lee, Dong-Hee;Noh, Sam-H.
    • Journal of KIISE:Computing Practices and Letters
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    • v.13 no.7
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    • pp.508-519
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    • 2007
  • Flash memory based storage has been used in various mobile systems and now is to be used in Laptop computers in the name of Solid State Disk. The Flash memory has not only merits in terms of weight, shock resistance, and power consumption but also limitations like erase-before-write property. To overcome these limitations, Flash memory based storage requires special address mapping software called FTL(Flash-memory Translation Layer), which often performs merge operation for block recycling. In order to reduce block recycling cost in NAND Flash memory based storage, we introduce another block recycling scheme which we call migration. As a result, the FTL can select either merge or migration depending on their costs for each block recycling. Experimental results with Postmark benchmark and embedded system workload show that this cost-based selection of migration/merge operation improves the performance of Flash memory based storage. Also, we present a solution of macroscopic optimal migration/merge sequence that minimizes a block recycling cost for each migration/merge combination period. Experimental results show that the performance of Flash memory based storage can be more improved by the macroscopic optimization than the simple cost-based selection.

Reliability Optimization Technique for High-Density 3D NAND Flash Memory Using Asymmetric BER Distribution (에러 분포의 비대칭성을 활용한 대용량 3D NAND 플래시 메모리의 신뢰성 최적화 기법)

  • Myungsuk Kim
    • IEMEK Journal of Embedded Systems and Applications
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    • v.18 no.1
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    • pp.31-40
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    • 2023
  • Recent advances in flash technologies, such as 3D processing and multileveling schemes, have successfully increased the flash capacity. Unfortunately, these technology advances significantly degrade flash's reliability due to a smaller cell geometry and a finer-grained cell state control. In this paper, we propose an asymmetric BER-aware reliability optimization technique (aBARO), new flash optimization that improves the flash reliability. To this end, we first reveal that bit errors of 3D NAND flash memory are highly skewed among flash cell states. The proposed aBARO exploits the unique per-state error model in flash cell states by selecting the most error-prone flash states and by forming narrow threshold voltage distributions (for the selected states only). Furthermore, aBARO is applied only when the program time (tPROG) gets shorter when a flash cell becomes aging, thereby keeping the program latency of storage systems unchanged. Our experimental results with real 3D MLC and TLC flash devices show that aBARO can effectively improve flash reliability by mitigating a significant number of bit errors. In addition, aBARO can also reduce the read latency by 40%, on average, by suppressing the read retries.

A method for optimizing lifetime prediction of a storage device using the frequency of occurrence of defects in NAND flash memory (낸드 플래시 메모리의 불량 발생빈도를 이용한 저장장치의 수명 예측 최적화 방법)

  • Lee, Hyun-Seob
    • Journal of Internet of Things and Convergence
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    • v.7 no.4
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    • pp.9-14
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    • 2021
  • In computing systems that require high reliability, the method of predicting the lifetime of a storage device is one of the important factors for system management because it can maximize usability as well as data protection. The life of a solid state drive (SSD) that has recently been used as a storage device in several storage systems is linked to the life of the NAND flash memory that constitutes it. Therefore, in a storage system configured using an SSD, a method of accurately and efficiently predicting the lifespan of a NAND flash memory is required. In this paper, a method for optimizing the lifetime prediction of a flash memory-based storage device using the frequency of NAND flash memory failure is proposed. For this, we design a cost matrix to collect the frequency of defects that occur when processing data in units of Drive Writes Per Day (DWPD). In addition, a method of predicting the remaining cost to the slope where the life-long finish occurs using the Gradient Descent method is proposed. Finally, we proved the excellence of the proposed idea when any defect occurs with simulation.

A Cleaning Policy for Mobile Computers using Flash Memory (플래시메모리를 사용하는 이동컴퓨터에서 클리닝 정책)

  • 민용기;박승규
    • Proceedings of the IEEK Conference
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    • 1998.10a
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    • pp.495-498
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    • 1998
  • Mobile computers have restrictions for size, weight, and power consumption that are different from traditional workstations. Storage device must be smaller, lighter. Low power consumed storage devices are needed. At the present time, flash memory device is a reasonable candidate for such device. But flash memory has drawbacks such as bulk erase operation and slow program time. This causes of worse average write performances. This paper suggests a storage method which improves write performance.

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A New Flash-aware Buffering Scheme Supporting Virtual Page Flushing

  • Lim, Seong-Chae
    • International Journal of Internet, Broadcasting and Communication
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    • v.14 no.3
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    • pp.161-170
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    • 2022
  • Recently, NAND-type flash memory has been regarded to be new promising storage media for large-scale database systems. For flash memory to be employed for that purpose, we need to reduce its expensive update cost caused by the inablity of in-place updates. To remedy such a drawback in flash memory, we propose a new flash-aware buffering scheme that enables virtual flushing of dirty pages. To this end, we slightly alter the tradional algorithms used for the logging scheme and buffer management scheme. By using the mechanism of virtual flushing, our proposed buffering scheme can efficiently prevent the frequenct occureces of page updates in flash storage. Besides the advantage of reduced page updates, the proposed viurtual flushing mechanism works favorably for shorneing a recocery time in the presense of failure. This is because it can reduce the time for redo actions during a recovry process. Owing to those two benefits, we can say that our scheme couble be very profitable when it is incorporated into cutting-edge flash-based database systems.